A) Upright lens configuration. B) Inverted lens configuration.


Scanning electron microscope  image of  pollen  (false colors)


Microscopic examination in a biochemical laboratory


Antonie van Leeuwenhoek  (1632–1723)


Stereo microscope


A  diatom  under Rheinberg illumination


Phase-contrast  light micrograph  of undecalcified  hyaline cartilage  showing  chondrocytes  and  organelles ,  lacunae  and  extracellular matrix


Images may also contain  artifacts . This is a  confocal laser scanning   fluorescence   micrograph  of  thale cress  anther (part of  stamen ). The picture shows among other things a nice red flowing collar-like structure just below the anther. However, an intact thale cress stamen does not have such collar, this is a fixation artifact: the stamen has been cut below the picture frame, and  epidermis  (upper layer of cells) of stamen stalk has peeled off, forming a non-characteristic structure. Photo: Heiti Paves from  Tallinn University of Technology .


Mathematically modeled Point Spread Function of a pulsed THz laser imaging system. [ 31 ]


Example of super-resolution microscopy. Image of  Her3  and  Her2 , target of the  breast cancer  drug  Trastuzumab , within a cancer cell.


Human cells imaged by DHM phase shift (left) and  phase contrast microscopy  (right)


Photoacoustic micrograph of human red blood cells.


TMPD


DMPD


Papanicolaou stain showing a low-grade  squamous intraepithelial lesion  (LSIL) from a  Pap test .  Cell nuclei  stained blue.


Figure 1 : In this phase shift image of cells in culture, the height and color of an image point correspond to the measured phase shift. The phase shift induced by an object in an image point depends only on the object thickness and the relative  refractive index  of the object in the image point. The volume of an object can therefore be determined from a phase shift image when the difference in refractive index between the object and the surrounding media is known. [ 3 ]


Negative selection  through replica plating to  screen  for ampicillin sensitive colonies


A sterile velvet on a plastic block for replica plating


Rhodamine B solution in water


Rhodamine B closed form (A) and open form (B)


A plate which has been streaked showing the colonies thinning as the streaking moves clockwise.


Illustration of streak plate procedure to achieve isolated colonies using aseptic technique.


Different labs have different standards as to the direction and style of the streaking.


Diagram


One of the microcinematographs used at the Marey Institute during the late 19th century


The electron microscope can achieve a resolution of up to 100  picometers , allowing eukaryotic cells, prokaryotic cells, viruses,  ribosomes , and even single atoms to be visualized (note the  logarithmic scale ).


Workflow of transmission electron microscopy DNA sequencing


Electron microscopy image of DNA: ribosomal transcription units of Chironomus pallidivitatus . This image was recorded with relatively old technology (ca. 2005).


This plated viability assay measures various yeast viability though a method called "frogging". The research is completed through drop-inoculation techniques. Research has since been conducted on "tadpoling", which is a variation of "frogging" that is completed by keeping the test cells diluted in liquid throughout their examination. [ 1 ]


Flow cytometry  using  7-Aminoactinomycin D  (7-AAD), wherein a lower signal indicates viable cells. Therefore, this case shows good viability (viability of the cells in flow cytometry should be around 95% but not less than 90%. [ 8 ] ).


Scanning electron micrograph  of  M. tuberculosis


Chain of infection; the chain of events that lead to infection


Infection of an  ingrown toenail ; there is pus (yellow) and resultant inflammation (redness and swelling around the nail).


This image depicts the steps of pathogenic infection. [ 18 ] [ 19 ] [ 20 ]


A southern house mosquito ( Culex quinquefasciatus ) is a  vector  that transmits the pathogens that cause  West Nile fever  and  avian malaria  among others.


Four  nutrient agar  plates growing colonies of common  Gram negative  bacteria


Nucleic acid testing conducted using an Abbott Laboratories ID Now device


A temporary drive-in testing site for COVID-19 set up with tents in a parking lot


Washing one's hands, a form of  hygiene , is an effective way to prevent the spread of infectious disease. [ 69 ]


Mary Mallon  (a.k.a. Typhoid Mary) was an asymptomatic carrier of  typhoid fever . Over the course of her career as a cook, she infected 53 people, three of whom died.


Deaths due to infectious and parasitic diseases per million persons in 2012:     28–81    82–114    115–171    172–212    213–283    284–516    517–1,193    1,194–2,476    2,477–3,954    3,955–6,812


Disability-adjusted life year  for infectious and parasitic diseases per 100,000 inhabitants in 2004: [ 86 ]    no data    ≤250    250–500    500–1000    1000–2000    2000–3000    3000–4000    4000–5000    5000–6250    6250–12,500    12,500–25,000    25,000–50,000    ≥50,000


The  Great Plague of Marseille  in 1720 killed 100,000 people in the city and the surrounding provinces.


Herrerasaurus  skull


Smallpox vaccine needle


Charcot's triad


Diagram showing liver and related parts of the digestive system


Cholangiogram  through a nasobiliary drain showing the common bile duct in black (diagonally from top left to bottom right in the center) with an interruption in the contour due to a large  gallstone .


Typhoid Mary  in a 1909 newspaper illustration. Mary Mallon was an asymptomatic carrier of  Salmonella typhi  who is thought to have infected 53 others with  typhoid fever  while continuing her work as a cook.


Typhoid Mary  in a New York Hospital


Contaminated currency  such as banknotes frequently used for snorting may spread  hepatitis C [ 1 ]


Brain abscess after metastasis treatment.


MRI (T1 with contrast) showing the ring-enhancing lesion. From a rare case report of an abscess formed as a complication of the CSF shunt. Jamjoom et al., 2009. [ 1 ]


Ancylostoma braziliense  mouthparts


Immunofluorescence micrograph of three  cytotoxic T cells  (outer three) surrounding a cancer cell. Lytic granules (red) are secreted at the contact site, killing the target. Cytotoxic T cells are powerful agents of cellular immunity.


Mobile chest photofluorography car in  Almaty , Kazakhstan


Model of a mobile mass miniature X-ray unit: Science Museum


Climate change is altering the geographic range and seasonality of some insects that can carry diseases, for example  Aedes aegypti , the mosquito that is the  vector  for  dengue  transmission.


Cyanobacteria  (blue-green algae) bloom on  Lake Erie  (United States) in 2009. These kinds of algae can cause harmful algal blooms.


Deaths due to malaria per million persons in 2012     0–0    1–2    3–54    55–325    326–679    680–949    950–1,358


Past and current malaria prevalence in 2009


This figure shows how the  Flavivirus  is carried by  mosquitos  in the  West Nile virus  and  Dengue fever . The mosquito would be considered a  disease vector .


The  deer tick , a vector for  Lyme disease  pathogens


A tick crawling on a human head in a wooded area near  LeRoy, Michigan .


A sheep infected with bluetongue virus.


An  Anopheles stephensi  mosquito shortly after obtaining blood from a human (the droplet of blood is expelled as a surplus). This mosquito is a vector of  malaria , and mosquito control is an effective way of reducing its incidence.


Infant with skin lesions from congenital rubella


"Salt-and-pepper" retinopathy is characteristic of congenital rubella. [ 6 ] [ 7 ]


Congenital rubella serology timeline


Cowpox (variola vaccina) pustules on a cow's udder


In  The Cow-Pock—or—the Wonderful Effects of the New Inoculation!  (1802),  James Gillray  caricatured recipients of the vaccine developing cow-like appendages.


Double-stranded RNA makes mRNA and genomic RNA using RNA-dependent RNA polymerase


Abscess originating from a tooth, that has spread to the  buccal space .  Above : deformation of the cheek on the second day.  Below : deformation on the third day.


Tooth#4, the maxillary right second premolar (upper right 2nd bicuspid), after extraction.  The two single-headed arrows point to the  CEJ , which is the line separating the  crown  (in this case, heavily decayed) and the roots.  The double headed arrow  (bottom right)  shows the extent of the abscess that surrounds the apex of the  palatal  root.


A dental infection resulting in an abscess and inflammation of the maxillary sinus


CT scan showing a large tooth abscess  (right in the image)  with significant inflammation of fatty tissue under the skin


An infected disc at the level of C5 C6 causing neurological symptoms


Percentage of stool samples from US states found to contain various protozoa in 2000 [ 44 ]


Number of stool samples from Canadian Lab found to contain various protozoa in 2005 [ 45 ]


Rabies virus


Spinal tap on a newborn


Encephalitis deaths per million persons in 2012     0-0    1-1    2-2    3-4    5-9    10-14    15-24    25-45


Human alphaherpesvirus 3  virion − a  herpesvirus  known to infect humans. It causes  chickenpox (varicella) , a disease most commonly affecting children, teens, and young adults, and  shingles (herpes zoster)  in adults.


Detecting whether medics have inadvertently transferred fluids to their clothing during a training sequence using simulated bodily fluids carrying an  ultraviolet  dye


Illustration from circa 1890 advertisement for a "Compound Vapor Bath" recommended for rheumatics


Bristol stool chart


Salmonella enterica  serovar Typhimurium (ATCC 14028) as seen with a microscope at 1000 fold magnification and following Gram staining


Percentage of rotavirus tests with positive results, by surveillance week, United States, July 2000 – June 2009


Deaths due to diarrhoeal diseases per million persons in 2012     0–2    3–10    11–18    19–30    31–46    47–80    81–221    222–450    451–606    607–1799


Disability-adjusted life year  for diarrhea per 100,000 inhabitants in 2004              no data       ≤500       500–1000       1000–1500       1500–2000       2000–2500       2500–3000           3000–3500       3500–4000       4000–4500       4500–5000       5000–6000       ≥6000


Map with the main travels of the  Age of Discovery  (began in 15th century).


Contemporary engraving of  Naples  during the  Naples Plague  in 1656


Worldwide distribution of plague-infected animals, 1998


An early medical illustration of people with syphilis, Vienna, 1498


New cases of leprosy in 2016


Past and current malaria prevalence in 2009


In 2007, the prevalence of TB per 100,000 people was highest in  Sub-Saharan Africa , and was also relatively high in Asian countries like  India .


Estimated HIV/AIDS prevalence among young adults (15-49) by country as of 2008


Cases of Ebola fever in Africa since 1976


Diagram showing horizontal transmission of a symbiont in its host.


Mortality rates 1841–1846 in two clinics documented by Semmelweis


Pneumonia as seen on chest x-ray.   A : Normal chest x-ray.  B : Abnormal chest x-ray with shadowing from pneumonia in the right lung (left side of image).


Hutchinson's teeth resulting from congenital syphilis


In some diseases, as depicted in this diagram, the latency period is shorter than the incubation period. After the latency period (but before clinical infection) the infected person can transmit the disease without signs of any symptoms. Such infection is called subclinical infection.


Helicobacter pylori


The relationship between the  latent period , the infectious period (the period of communicability) and the  incubation period . In some diseases, as depicted in this diagram, the latent period is shorter than the incubation period. A person can transmit an infection without showing any signs of the disease. Such an infection is called a  subclinical infection .


Sports centre requisitioned for the isolation and care of people infected with  coronavirus disease 2019 , in  Wuhan  (China).


A scanning electron micrograph (SEM) depicting a number of Gram-negative  Bordetella bronchiseptica  bacteria.


Transmission electron micrograph of parainfluenza virus. Two intact particles and free filamentous nucleocapsid.


Robert Hermann Koch (11 December 1843 – 27 May 1910) was a  German   physician  who developed Koch's postulates. [ 1 ]


Koch's postulates of disease.


In some diseases, as depicted in this diagram, the latent period is shorter than the  incubation period . In such cases, a person can transmit infection without showing any signs of the disease and is called subclinically infectious or an  asymptomatic carrier


Deaths from lower respiratory infections per million persons in 2012:     24-120    121-151    152-200    201-241    242-345    346-436    437-673    674-864    865-1,209    1,210-2,085


Disability-adjusted life year  for lower respiratory infections per 100,000 inhabitants in 2004: [ 18 ]      no data      less than 100      100–700      700–1,400      1,400–2,100      2,100–2,800      2,800–3,500      3,500–4,200      4,200–4,900      4,900–5,600      5,600–6,300      6,300–7,000      more than 7,000


Human mycetoma in India in 2013 [ 4 ]


Bighorn sheep tagging after  Mycoplasma ovipneumoniae  testing


On-site testing for  Mycoplasma ovipneumoniae  in Hells Canyon


Bighorn Sheep capture in Hells Canyon for ' Mycoplasma ovipneumoniae  testing


The internal air is forced out so that negative air pressure is created pulling air passively into the system from other inlets.


Inside view of a negative pressure isolation chamber for patients with contagious diseases.


Schematic of a network of rooms where air (shown in blue) flows in one direction from the corridor into the negative pressure room (green). Exhaust air is safely removed from the area through a ventilation system.


A young boy from  Panama  with  Chagas disease . It has manifested as an acute infection with swelling of one eye (chagoma).


Dracunculus medinensis  larvae


Lifecycle of  Echinococcus


A child with yaws


Fasciola hepatica


Lifecycle of African Trypanosomiasis


Lifecycle of Leishmaniasis


Hands deformed by leprosy


Elephantiasis


Onchocerca volvulus  emerging from a blackfly


Rabies virus


11-year-old Filipino boy with  ascites  due to schistosomiasis


Adult ascaris worms being removed from the bile duct of a patient in South Africa


Eliminating NTDs in  Côte d'Ivoire  through education and distribution of anti-parasitic drugs


School nurse checks student's health in Kenya


Global overlap of six of the common NTDs, specifically guinea worm disease, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths, and trachoma, in 2011


The structure of two of the ivermectins, an important class of drug in the control of Onchocerciasis.


Melinda and Bill Gates speak during press conference at the World Economic Forum in Davos, Switzerland, January 30, 2009.


The Drugs for Neglected Diseases Initiative, a web-focused not-for-profit drug R&D organization dedicated to creating new NTD treatments.


Chorioamnionitis


Bernardino Ramazzini


Sir Robert Peel


Harry McShane, age 16, 1908. Pulled into machinery in a factory in  Cincinnati  and had his arm ripped off and his leg broken without any compensation. [ 22 ]


Various health and safety warning campaigns have sought to reduce workplace hazards, such as this one about ladder safety.


Rollover protection bar  on a  Fordson  tractor


Beekeeper  wearing protective clothing


Construction workers not wearing fall protection equipment


Workplace safety notices at the entrance of a Chinese construction site


Leather craftsman gloves, safety  goggles , and a properly fitted  hard hat  are crucial for proper safety in a construction environment


Proportion of disease-specific work-related mortality in 2019, globally, with 95% confidence intervals [ 75 ]


Deaths due to long working hours per 100,000 people (15+), joint study conducted by  World Health Organization  and  International Labour Organization  in 2016


Average annual hours actually worked per worker in  OECD  countries from 1970 to 2020


Share of number of employees engaged in hazardous and/or dangerous working conditions in Russia between 1993 and 2017 [ 79 ]


Number of occupational fatal work injuries in the US from 1992 until 2014 (2001 statistics do not include deaths related to the  11 September terrorist attacks .)


Rate of fatal work injuries per 100,000 full-time equivalent workers by employee status, 2006–17. Rate = (fatal work injuries/total hours worked by all workers) × 200,000,000 where 200,000,000 = base for 100,000 full-time equivalent workers (FTEs) working 40 hours per week, 50 weeks per year. Total hours worked are annual average estimates from the  Current Population Survey  (CPS).


Hardware stores in China specializing in safety equipment


AI-enabled  wearable  sensor networks may improve worker safety and health through access to real-time, personalized data, but also present psychosocial hazards such as  micromanagement , a perception of  surveillance , and  information security  concerns.


Automated guided vehicles are examples of cobots. Use of AI to operate these robots may result in physical hazards such as the robot colliding with workers.


A containment hood protecting workers handling nanomaterials


Respiratory droplets are released through talking, coughing, or sneezing. [ 15 ]


Brocky, Karoly - Mother and Child (1846-50)


1940 US WPA poster encouraging modernized privies


A normal throat


Exudative  pharyngitis in a person with  infectious mononucleosis


A case of strep throat


Throat swab


Main symptoms of infectious pneumonia


The bacterium  Streptococcus pneumoniae , a common cause of pneumonia, imaged by an  electron microscope


Cavitating pneumonia due to MRSA as seen on a CT scan


A chest x-ray of a patient with severe viral pneumonia due to  SARS


Pneumonia fills the lung's  alveoli  with fluid, hindering oxygenation. The alveolus on the left is normal, whereas the one on the right is full of fluid from pneumonia.


A chest X-ray showing a very prominent wedge-shaped area of airspace consolidation in the right lung characteristic of acute bacterial lobar pneumonia


CT of the chest demonstrating right-sided pneumonia (left side of the image)


A  pleural effusion : as seen on chest X-ray. The A arrow indicates fluid layering in the right chest. The B arrow indicates the width of the right lung. The volume of the lung is reduced because of the collection of fluid around the lung.


Deaths from lower respiratory infections per million persons in 2012     24–120    121–151    152–200    201–241    242–345    346–436    437–673    674–864    865–1,209    1,210–2,085


Disability-adjusted life year  for lower respiratory infections per 100,000 inhabitants in 2004 [ 143 ]      no data      less than 100      100–700      700–1,400      1,400–2,100      2,100–2,800      2,800–3,500      3,500–4,200      4,200–4,900      4,900–5,600      5,600–6,300      6,300–7,000      more than 7,000


WPA  poster, 1936/1937


Chart showing symptoms of long COVID


Cells infected with  Epstein–Barr virus , one of the viruses implicated in PAISs


ME/CFS has many competing definitions.


In his 1861 book,  Ignaz Semmelweis  presented evidence to demonstrate that the advent of  pathological anatomy  in Vienna in 1823 (vertical line) was correlated to the incidence of fatal childbed fever there. Onset of  chlorine  handwash in 1847 marked by vertical line. Rates for Dublin maternity hospital, which had no pathological anatomy, is shown for comparison ( view rates ). His efforts were futile, however.


Q flag


Rabies prevention efforts in India, which accounts for 36% of the world's rabies deaths [ 1 ]


A stray dog with an ear tag, indicating that it has been part of a  trap–neuter–return  program, a policy enacted in many countries in order to prevent the spread of rabies


Managing stray dogs, by vaccination or removal from the streets, is necessary in order to prevent rabies. It is estimated that there are about 62 million stray dogs in India. [ 7 ]


Cases of animal rabies in the United States in 2001


A rabid dog, with saliva dripping out of the mouth


A fox in Romania. Foxes and stray dogs are considered to be at highest risk of rabies in Romania. [ 104 ]


Map of rabies-free countries and territories


Stray  Askals  in the Philippines. Lack of awareness about rabies prevention can lead to tourists dying from contracting the disease. [ 123 ]


PrP Sc  (stained in red) revealed in a photomicrograph of scrapie-infected mouse neuronal cells.


Models of normal (PrP C ) and infectious (PrP Sc ) forms of prion protein on a membrane: polypeptide (turquoise); glycans (red); glycolipid anchors (blue). The core structures are based on NMR spectroscopy (PrP C ) and cryo-electron microscopy (PrP Sc ).


Heterodimer model of prion propagation


Fibril model of prion propagation.


Photomicrograph of Prototheca wickerhamii infection in a human. Note the floret-like arrangements. Hematoxylin and eosin stain.


Photomicrograph of Prototheca wickerhamii infection in a human. Note the floret-like arrangements. Gomori methenamine silver(GMS) stain.


Photomicrograph of Prototheca wickerhamii infection in a human. Note the floret-like arrangements. Periodic acid-Schiff(PAS) stain.


Animals with "dumb" rabies appear depressed, lethargic, and uncoordinated


A young girl about to receive PEP after being bitten by an animal thought to be rabid


Rabies cases in humans and domestic animals – United States, 1938–2018


Two dogs with the paralytic, or dumb, form of rabies


Respiratory system  anatomy


Deaths from respiratory infections per million persons in 2012     24-120    121-151    152-200    201-244    245-346    347-445    446-675    676-866    867-1,209    1,210-2,090


The malaria parasite life cycle involves two hosts.


"African trypanosomes" or "Old World trypanosomes" are protozoan hemoflagellates of the genus Trypanosoma, in the subgenus Trypanozoon.


Arbovirus in the urban cycle jumping to the wild maintenance cycle due to the Aedes aegypti vector infecting non-human primates or viremic individuals infecting the wild mosquito.


Confronting data sparsity to identify potential sources of Zika virus spillover infection among primates


Case studies of reverse zoonoses by animal and disease type before 2014


Nelson, M. I., & Vincent, A. L. (2015). Reverse zoonosis of influenza to swine: new perspectives on the human-animal interface. Trends in microbiology, 23(3), 142–153.  https://doi.org/10.1016/j.tim.2014.12.002


Colonies of the bacterial sapronosis  Legionella pneumophila


Patient of an  intensive care unit  of a German hospital (2015) with severe sepsis caused by a  chain reaction  of incidental negative events after a prior surgery of the  abdomen . After an emergency surgery, he received  antibiotics ,  parenteral nutrition  and  pain killers  via automated injection employing  infusion pumps  (background right).  Hemodialysis  via the machine on the left became necessary due to  kidney  malfunction and  multiple organ dysfunction syndrome . After three months in the hospital, the patient recovered within a month and has since then fully recovered (as of 2023).


Blood culture  bottles: orange cap for  anaerobes , green cap for  aerobes , and yellow cap for blood samples from children [ 44 ]


Sepsis Steps. Training tool for teaching the progression of sepsis stages


Intravenous fluids being given


Personification of  septicemia , carrying a spray can marked " Poison "


Phenotypic strategy switches of microbes capable of provoking sepsis


People socially distancing while  queuing  to enter a supermarket in London during the  COVID-19 pandemic


Without social distancing and other pandemic containment measures, pathogens can spread exponentially. [ 1 ]  This graphic shows how early adoption of containment measures tends to protect wider swaths of the population.


Social distancing helps prevent a sharp peak of infections ("flattens the  epidemic curve ") to help healthcare services deal with demand, and extends time for healthcare services to be increased and improved. [ 19 ] [ 20 ] [ 21 ] [ 22 ]


Social distancing includes eliminating the physical contact that occurs with the typical  handshake ,  hug , or  hongi ; this New Zealand illustration offers eight alternatives.


Muslims in Indonesia  pray in congregation  while imposing to strict physical-distancing protocols during the  COVID-19 pandemic . During the pandemic, Mosques in Indonesia has also removed the indoor rugs and has ordered worshipers to bring their own personal prayer rugs to prevent the spreading of the virus. Some mosques which are located in the most infected regions even are ordered to be closed for worship


Swine flu cases per week in the United Kingdom in 2009; schools typically  close for summer  in mid-July and re-open in early September. [ 42 ]


VE Day  celebrations in 2020 took place under lockdown; here a socially distanced street party is taking place on  Hallfield Estate ,  Wetherby .


Simulations comparing rate of spread of infection, and number of deaths due to overrun of hospital capacity, when social interactions are "normal" (left, 200 people moving freely) and "distanced" (right, 25 people moving freely). Green = Healthy, uninfected individuals Red = Infected individuals Blue = Recovered individual Black = Dead individuals [ 95 ]


Typhoid Mary , pictured above in a 1909 tabloid, was a famous case of a subclinical infection of  Salmonella enterica serovar .


9th floor layout of the Hotel Metropole in  Hong Kong , showing where a superspreading event of  severe acute respiratory syndrome  (SARS) occurred in 2003


How an infection spreads in a community with immunized and non-immunized members.


Guangdong Province in southeastern China where the first outbreak of SARS occurred in 2003.


Rates of  measles vaccination  worldwide in 2010


Primary syphilis on a tongue


Chancre on a penis due to primary syphilis, 1978


Typical presentation of secondary syphilis with a rash on the palms of the hands, 1967


Reddish  papules  and  nodules  over much of the body due to secondary syphilis


Model of a head of a person with tertiary (gummatous) syphilis,  Musée de l'Homme , Paris


Histopathology  of  Treponema pallidum  bacteria using a modified  Steiner silver stain , 1986


This  Works Progress Administration  poster ( c.  1936) acknowledges the social stigma of syphilis, while urging those who possibly have the disease to be tested


Micrograph  of secondary syphilis skin lesions. (A/B) H&E stain of SS lesions. (C/D) IHC staining reveals abundant bacteria embedded within a mixed cellular inflammatory infiltrate (shown in the red box) in the papillary dermis. The blue arrow points to a tissue histiocyte and the read arrows to two dermal lymphocytes [ 40 ]


Portrait of a man affected with what is now believed to have been congenital syphilis,  c.  1820 [ 49 ]


Jarisch–Herxheimer reaction in a person with syphilis and human immunodeficiency virus [ 71 ]


Syphilis deaths per million persons in 2012     0–0    1–1    2–3    4–10    11–19    20–28    29–57    58–138


Age-standardized   disability adjusted life years  from syphilis per 100,000 inhabitants in 2004 [ 75 ]              no data      <35      35–70      70–105      105–140      140–175      175–210          210–245      245–280      280–315      315–350      350–500      >500


Portrait of  Gerard de Lairesse  by  Rembrandt van Rijn , circa 1665–67, oil on canvas. De Lairesse, himself a painter and art theorist, had congenital syphilis that deformed his face and eventually blinded him [ 85 ]


A healthy man and a diseased man torture  Christ  before  his crucifixion . From a Frensh  book of hours ,  c.  1375–1435


An early medical illustration of people with syphilis, Vienna, 1498


A  Work Projects Administration  poster about syphilis c. 1940


Preparation and Use of Guayaco for Treating Syphilis , after  Stradanus , 1590


Age-standardized  death from syphilis per 100,000 inhabitants in 2004. [ 1 ]      no data    <35    35–70    70–105      105–140      140–175    175–210      210–245      245–280      280–315      315–350      350–500      >500


Syphilis cases by gender, transmission category and year in EU/EEA countries reporting consistently, 2012–2021


Syphilis—Reported Cases by Stage of Infection, United States, 1941–2009.


Rates of syphilis by gender in the United States.


Activation of macrophage or B cell by T helper cell


T-cell dependent B-cell activation, showing TH2-cell (left) B-cell (right) and several interaction molecules self-made according to Janeway et al,  Immunologie  (Berlin, 2002)


Antigen presentation stimulates naïve CD8+ and CD4+ T cells to become mature  "cytotoxic" CD8+ cells  and "helper" CD4+ cells respectively .


T h 1/T h 2 Model for helper T cells. An antigen is ingested and processed by an  APC . It presents fragments from it to T cells. The upper, T h 0, is a T helper cell. The fragment is presented to it by  MHC2 . [ 24 ]  IFN-γ,  interferon γ ; TGF-β,  transforming growth factor β ; mø,  macrophage ; IL-2,  interleukin 2 ; IL-4,  interleukin 4


Disability-adjusted life year  for tropical diseases per 100,000 inhabitants. These include  trypanosomiasis ,  chagas disease ,  schistosomiasis ,  leishmaniasis ,  lymphatic filariasis ,  onchocerciasis .      no data      ≤100      100–200      200–300      300–400      400–500      500–600      600–700      700–800      800–900      900–1000      1000–1500      ≥1500


Time line for cold symptoms


Upper respiratory infections deaths per million persons in 2012     0    1    2    3–29


Disability-adjusted life year  for URTIs per 100,000 inhabitants in 2002: [ 25 ]      no data      less than 10      10–30      30–60      60–90      90–120      120–150      150–180      180–210      210–240      240–270      270–300      more than 300


Urine may contain pus (a condition known as  pyuria ) as seen from a person with  sepsis  due to a urinary tract infection.


Uropathogenic  Escherichia coli  (UPEC)  cells adhered to bladder epithelial cell


Bladder infection


Multiple  bacilli  (rod-shaped bacteria, here shown as black and bean-shaped) shown between white blood cells in urinary microscopy. These changes are indicative of a urinary tract infection.


Trimethoprim-Sulfamethoxazole tablets, a commonly used antibiotic for UTI.


A child being immunized against  polio


Evolution mechanisms of Influenza A virus. (A)  Antigenic Drift : Gradual accumulation of mutations in the genome of IAVs leads to emergence of new virus variants. (B)  Antigenic Shift : The reassortment of genetic segments between two or more invading IAVs in a host cell can lead to emergence of an antigenically novel subtype.


A typical virus replication cycle


Some bacteriophages inject their  genomes  into bacterial cells (not to scale)


The Baltimore Classification of viruses is based on the method of viral  mRNA  synthesis


Overview of the main types of viral infection and the most notable species involved [ 107 ]


Transmission electron microscope  image of a recreated 1918 influenza virus


Two  rotaviruses : the one on the right is coated with antibodies that prevent its attachment to cells and infecting them.


The structure of the DNA base  guanosine  and the antiviral drug  acyclovir


Peppers  infected by mild mottle virus


Transmission electron micrograph of multiple bacteriophages attached to a bacterial cell wall


Scientist studying the  H5N1  influenza virus


A sketch of two women suffering from Winterbottom's Sign


A gorilla licking a wound


A dog licking a wounded paw


A cat with an  Elizabethan collar


Lick granuloma  from excessive licking


Possibilities for zoonotic disease transmissions


Selman Waksman , who was awarded the Nobel Prize in Medicine for developing 22 antibiotics—most notably  Streptomycin


Illustrative scheme of photodynamic reactions. The photosensitizer absorbs light and is promoted from its ground  singlet state  ( 1 PS) to an excited singlet state ( 1 PS*). Alternatively, the photosensitizer can convert to an excited  triplet state  ( 3 PS*) by  intersystem crossing . This is a longer-living state that allow sufficient time for chemical reactions to occur. A photosensitizer in  3 PS* state can return to  ground state  ( 1 PS) either by emitting  phosphorescence , or by  photochemical reactions  that occur through transfer of charges or energy. These photochemical reactions can locally generate cytotoxic  reactive oxygen species  (ROS) via the Type I or II photodynamic reactions. In a cellular microenvironment, these ROS have a short lifespan (<10μs), and react with and destroy biomolecules, such as proteins, carbohydrates, nucleic acids, and lipids, very close (<1μm) to the production site. Type I: Charges, such as  electrons , are transferred to surrounding substrates (R), forming  radicals  (R • ) due to the presence of the unpaired electron that was received. Molecular oxygen (O 2 ) participates directly or indirectly in this reaction pathway forming the radical anion known as  superoxide  (O 2 •– ). The superoxide radical can be further reduced to form  hydrogen peroxide  (H 2 O 2 ), which can also be reduced to form highly reactive free  hydroxyl radicals  (HO • ) via  Fenton-like reactions . Type II: Energy is transferred to ground state triplet molecular oxygen ( 3 O 2 ), creating  singlet oxygen  ( 1 O 2 *), an excited form of oxygen that is much more reactive than its ground state triplet counterpart.  1 PS = Ground Singlet State of Photosensitizer;  1 PS* = First Excited Singlet State of Photosensitizer;  3 PS* = First Excited Triplet State of Photosensitizer; ISC = Intersystem Crossing;  3 O 2  = Ground State Triplet Oxygen;  1 O 2  = Excited State Singlet Oxygen.


Molecular frameworks most often used as photosensitizers for antimicrobial photodynamic therapy. The examples listed in this figure include:  methylene blue  (MB,  phenothiazine ),  crystal violet  (CV,  triarylmethane ),  porphyrins ,  phtalocyanines ,  riboflavin  (Vitamin B 2 ),  rose bengal  (RB, halogenated  xanthene ),  chlorins  and  curcumin .


Electrostatic and hydrophobic interaction of an antimicrobial polymer and biomimetic polymer, causing membrane disruption and cell death. [ 8 ]


Schematic of the antimicrobial mechanism of action, [ 10 ]  demonstrating the antimicrobial mechanism of polymers


Quaternized N-alklyl Chitosan


Incorporation of  bithionol  into the polymer backbone


A copper alloy pen that has been deployed on a  fish farm  at depth of 14 feet for one year shows no signs of  biofouling .


Arachidonic acid inflammatory cascade


Dispersive forces of grafted polymer chains can prevent bacterial adhesion to a surface


Contact angle of a liquid droplet wetted to a rigid solid surface.


Wenzel model


Ball and stick model of DBNPA


Spacefill model of DBNPA


Dichlor


3D structure of Formaldehyde


Hexamethylenetetramine from  Bayer  ( IG Farben )


On the left is leuco-malachite Green (LMG) and on the right are the two equivalent  resonance structures  of the MG cation. The alcohol derivative of MG is derived from LMG by replacement of the unique C–H by C–OH.


Synthesis of malachite green


A preparation of  Bacillus subtilis  showing  endospores  stained with malachite green (vegetative cells stained pink with safranin counterstain)


Streak plates  of several bacterial species on nutrient agar plates


Kirby–Bauer testing: White wafers containing  antibiotics  shown on plate of  bacteria . Circles of poor bacterial growth surround some wafers, indicating susceptibility to the antibiotic


100 mg Macrobid, Canada


Figure 1. Tirandamycin family of structures


Figure 2. Biosynthetic pathway of tirandamycins


Figure 3. TrdL in vitro activity


Figure 4. TamI and TamL post-translational modifications


Symclosene


ASM Microbe 2018 meeting in Atlanta


Academy Fellows’ reception at Microbe 2022 that pictures some of the newly elected fellows with the ASM president.


Gas-Pak jar


Immunofluorescence


API 20NE rapid test system, one day after sample application


Antibiotic susceptible bacteria


A positive CAMP test with the characteristic arrowhead shaped zone of hemolysis


Color transition of Methyl red solution under different acid-base conditions


TSI Agar


Raoultella planticola on urea agar


Tabletop centrifuge


Strawberries  dropped on the ground. The  five-second rule  suggests that if they are picked up within five seconds, it is safe to eat them without rewashing.


Portrait of  Genghis Khan


A microbiologist working in a biosafety laboratory tests for high risk pathogens in food


Food microbiology laboratory at the  Faculty of Food Technology ,  Latvia University of Life Sciences and Technologies


Representation of bioreactors. They are used to store the microbes while they are producing desired product of interest.


Schematic workflow for microbial factory optimization


Traumatic injuries, like those from improvised explosive devices, leave large open areas contaminated with debris that are vulnerable to becoming infected with  A. baumannii .


The logistics of transporting wounded soldiers result in patients visiting several facilities where they may acquire  A. baumannii  infections.


Aspergillus clavatus  colony growing on petri dish


Aspergillus flavus  in a petri dish


Electron micrograph of  Bacillus cereus


Bacillus cereus  endospore stain


Bacillus cereus colonies on the indicator media Brilliance Bacillus cereus agar


Regulation of sporulation in  B. subtilis


Gram-stained  B. subtilis


Colonies of  B. subtilis  grown on a  culture dish  in a  molecular biology   laboratory


Enteritis, a major complication of a  Campylobacter jejuni  infection, results in inflammation as pictured above, in which eosinophil aggregation occurs.


Scanning electron micrograph depicting a number of  Campylobacter jejuni  bacteria


Various stages in the life cycle of  Claviceps purpurea


fruiting bodies with head and stipe on  Sclerotium


Model of  Claviceps purpurea ,  Botanical Museum Greifswald


Sclerotium  of  Claviceps purpurea  on  Alopecurus myosuroides


Ergot-derived drug to stop postnatal bleeding


Sphacelia segetum  on  potato dextrose agar


This illustration depicts a three-dimensional (3D), computer-generated image of a cluster of barrel-shaped,  Clostridium perfringens  bacteria. The artistic recreation was based upon scanning electron microscopic (SEM) imagery.


Vaginal squamous cell with normal  vaginal flora  versus  bacterial vaginosis  on  Pap stain . Normal vaginal flora (left) is predominantly rod-shaped  Lactobacilli , whereas in bacterial vaginosis (right) there is an overgrowth of bacteria, which can be of various species.


Dental caries


Conjugation


Crushed hop


Gram-positive cellwall-schematic


Clue cells - CDC PHIL 3720


Chromogenic agar can help in indicating  P. kudriavzevii  infection versus some similar fungi. (CHROMAgar shown)


Gem-shaped sporangiospores of  R. stolonifer  showing characteristic striations.


R. stolonifer  colonizing a strawberry.


Staphylococcus aureus  on basic cultivation media


Hemolysis  on  blood agar ,  DNase  activity,  clumping factor ,  latex agglutination , growth on  mannitol-salt  and  Baird-Parker  agar,  hyaluronidase  production.


Gram stain of  S. saprophyticus  cells, which typically occur in clusters: The cell wall readily absorbs the  crystal violet  stain.


Key characteristics of  Staphylococcus aureus


3D medical animation still shot of osteomyelitis bone


This 2005  scanning electron micrograph  (SEM) depicts numerous clumps of  methicillin-resistant  S. aureus  (MRSA) bacteria.


S. aureus  on  trypticase soy agar :  The strain is producing a yellow pigment  staphyloxanthin .


Typical gram-positive cocci, in clusters, from a sputum sample, Gram stain


Bacterial cells of  S. aureus , which is one of the causal agents of  mastitis in dairy cows : Its large capsule protects the organism from attack by the cow's immunological defenses.


Susceptibility to commonly used antibiotics.


A  microscope  for  Trichinella  detection (from 1847).


TCBS agar  plate of  Vibrio Cholerae  (left) and  Vibrio parahaemolyticus  (right)


Cholera toxin interrupting regulation of adenyl cyclase inside the cell causing efflux of water and sodium into the intestinal lumen


Children in Mpape community play in a waste water drainage area. This drainage was the suspected source of contamination of the well water that led to the cholera outbreak investigated by Nigeria FELTP residents in April 2014. Two samples collected from home wells around this drainage tested positive for  Vibrio cholerae .


The process of fermentation at work on Pinot noir. As yeast consume the sugar in the  must  it releases alcohol and carbon dioxide (seen here as the foaming bubbles) as byproducts.


French scientist Louis Pasteur discovered the connection between microscopic yeast and the process of fermentation.


In the absence of oxygen, yeast cells will take the pyruvate produced by glycolysis and reduce it into acetaldehyde which is further reduced into ethanol "recharging" the NAD+ co-enzymes that is needed for various metabolic processes of the yeast.


If a Chardonnay has too much "buttery" diacetyl notes, winemakers may add fresh yeast to the wine to consume the diacetyl and reduce it to the more neutral-smelling fusel oil 2,3-Butanediol.


The distinctive "aldehydic" notes of  Sherry wines  are caused by special yeast native to the  Jerez wine region .


The lees left over from the secondary fermentation of sparkling wine can be seen on the bottom side of this bottle being inspected. Eventually this wine will go through riddling to collect the lees in the neck, where it will be removed prior to corking.


Film yeast on the surface of wine in a barrel of  Vin jaune  from the  Jura wine  region of France


Saccharomyces cerevisiae  as seen under a Differential Interference Contrast (DIC) microscope


While some strains of yeast may influence the sensory characteristics and aromas of young wine, these differences seem to fade as the wine ages.


Fruit flies are a common vector that transports ambient or "wild" yeast strains within wineries.


Wineries that wish to cultivate an "in-house" ambient yeast strain will often recycle the leftover pomace of previous vintages as compost in the vineyard.


Some winemakers favor the use of freeze-dried cultured yeast (left) and yeast nutrients (right) because of their relative predictability in beginning and completing a fermentation.


Preparing a yeast starter culture and gradually cooling the culture down to the must temperature by adding some wine


Diammonium phosphate (or DAP) is a common additive that provides two necessary nutrients for yeast to have a healthy and sustained fermentation – nitrogen and phosphate.


One traditional way of providing nutrients for the yeast is the  ripasso  method where the leftover grape skins and pomace  (pictured)  from a previous fermentation is added to a newly fermenting wine.


Film yeast like  Candida  ( pictured ) and  Pichia  can cover the surface of a wine with a film layer that not only consumed most of the free sulfur dioxide available to protect the wine but also produces high levels of acetic acid that will contribute to volatile acidity in a wine.


While some wine regions view the influence of  Brettanomyces  on the wine, in limited amounts, as added complexity, many winemakers view the presence of  Brettanomyces  species such as  Brettanomyces bruxellensis  ( pictured ) in their wineries as a negative influence that needs to be controlled.


Micropipette in action


Schematic diagram of an air displacement pipette. The "Digital volume indicator" is a dial display that indicates the digits (i.e. unrelated to electronic). The components vary between brands and different volume sizes have different components, for example the piston in a P2 is needle-like and can be separated with ease from the piston assembly whereas in a P10ML it is drum-like and over 1 cm in diameter and is enclosed in plastic.


Three air-displacement pipettes that handle different volumes.


Adjustable tip spacing pipette transferring samples from a 384 well plate to a 96 well plate


Autoclaved (left) and unautoclaved (right) autoclave tape


Schematic diagram of a Berkefeld filter


Berkefeld field filter


Class II Biosafety Cabinet Types using color to illustrate where it is safe to handle hazardous chemistry with microbiology. (Blue is recirculated air where it is NOT safe to use hazardous chemistry. Red is single pass air and is safe for chemical use. Purple is uncertainty due to location of the BSCs smoke-split)


A researcher observing a specimen through the built-in microscope in a Class III biosafety cabinet


Aerosol  control platform inside a Class III Biosafety Cabinet


Components of a Pasteur-Chamberland filter


Schematic diagram of a Chamberland filter


A cotton swab


A pack of 54 Q-tips


Wet-type earwax  on a cotton swab


Cotton swabs in a round container


Diagram of a Durham Tube


[ 1 ]  This table displays the steps involved in using a GasPak to create a completely anaerobic environment for incubating an inoculated agar plate. After inoculating the agar plate(s) with bacteria under aseptic conditions, the agar plates are placed in an anaerobic jar that contains components, like the catalyst chamber, that will help facilitate the reaction to eliminate free oxygen and provide completely anaerobic conditions. The methylene blue strip is an indicator that is placed in the jar that will turn colorless under entirely anaerobic conditions, which provides proof that the jar was able to successfully reach an anaerobic state. The components of the GasPak envelope along with the addition of water, allow for the start of the reaction that takes place in the catalyst chamber. The sealed anaerobic jar is then incubated at a desired temperature to allow growth of the bacteria. In the above figure for example, the incubation occurred at 100 °F (38 °C). A colorless indicator strip provides proof that the anaerobic conditions were met and the agar plates can now be observed for bacterial growth.


Hot air oven


Interior of a  CO 2  incubator used in  cell culture


A Bacteriological incubator


Reaumur thermometer


Incubator invented by Hess


Shaking incubator


A close up of an inoculation needle


Sterilization of an inoculation needle via alcohol burner


Stab Cultures after inoculation by inoculation needle with E. coli from left to right: TSI, Soft nutrient, Simmons Citrate agar


Inside a shaking water bath


A water bath operating at 72°C


Preparation of microbiological samples in a laminar chamber


McFarland standards. No. 0.5, 1 and 2


18th-century microscopes from the  Musée des Arts et Métiers ,  Paris


Carl Zeiss binocular compound microscope, 1914


Electron microscope constructed by  Ernst Ruska  in 1933


First atomic force microscope


Fluorescence microscope with the filter cube turret above the objective lenses, coupled with a camera


Types of microscopes illustrated by the principles of their beam paths


Evolution of spatial resolution achieved with optical, transmission (TEM) and aberration-corrected electron microscopes (ACTEM) [ 26 ]


Unstained cells viewed by typical brightfield (left) compared to phase-contrast microscopy (right)


Modern transmission electron microscope


Transmission electron micrograph of a dividing cell undergoing cytokinesis


Leaf surface viewed by a scanning electron microscope


Typical atomic force microscopy set-up


A glass Petri dish with culture


A Petri dish with  bacterial  colonies on an  agar -based  growth medium


Axenic  cell culture  of the plant  Physcomitrella patens  on an  agarplate  in a Petri dish


Principle of photoactivation


Single-Channel  Electronic Pipettes  designed to handle 0.5–10ml


VIAFLO electronic multichannel pipettes from INTEGRA Biosciences


Several sizes of volumetric pipette.


Pasteur pipettes with rubber bulbs attached.


A transfer pipette


Combustion pipette


A biochemist pipetting


A smart pipette stand that can control electronic pipettes


The upper part of a plankton net consisting of (1) towing line connected to (2) three-point bridle, which are responsible for holding the plankton net


A simple plankton net


Cod end—an outlet valve with collecting cylinder


Aquatic scientist casting a plankton net in  Brown's Lake Bog .


Rubber policemen


A type of policeman which is made of plastic and is formed into spatula shapes at the ends.


A picture of stainless steel laboratory policeman.


A traveling microscope. E— eyepiece ,  O— objective ,  K—knob for focusing, V—vernier, R—rails, S—screw for fine position adjustment.


Schematic of cell adhesion


Overview diagram of different types of cell junctions present in epithelial cells, including cell–cell junctions and cell–matrix junctions.


Adheren junction showing homophilic binding between cadherins and how catenin links it to actin filaments


Gap junctions showing connexons and connexins


Hemidesmosomes diagram showing interaction between integrins and laminin, including how integrins are linked to keratin intermediate filaments


Top: Under normal blood flow conditions, leukocytes (gray circles) float freely in the bloodstream. Bottom: Under conditions of infection and inflammation, high shear stress causes leukocytes to bind and roll along blood vessel walls (red lines). This is known as the shear-threshold phenomenon.


Catch-slip transition allows leukocytes to roll along blood vessel walls.


Allosteric model states that applied tension results in an extended conformation of the EGF domain, causing a conformational change to the lectin domain, resulting in increased binding affinity.


Image courtesy of Wikipedia user JWSchmidt under the GNU Free Documentation License


Myxococcus xanthus  visualized under a microscope.


M. xanthus  Fruiting Bodies are macroscopic and visible to the naked eye.


This image depicts a variety of types of bacterial locomotion


Two common modes of amoeboid motility


Diagram of the three main kinds of amoeboid cell movement


During  apoptosis , blebbing is the first phase (left) of cell disassembly. [ 1 ]


Chemical structure of blebbistatin [ 17 ]


Two different models for how cells move. A) Cytoskeletal model. B) Membrane Flow Model


(A) Dynamic microtubules are necessary for tail retraction and are distributed at the rear end in a migrating cell. Green, highly dynamic microtubules; yellow, moderately dynamic microtubules and red, stable microtubules. (B) Stable microtubules act as struts and prevent tail retraction and thereby inhibit cell migration.


Rearward membrane flow (red arrows) and vesicle trafficking from back to front (blue arrows) drive adhesion-independent migration. [ 26 ]


Schematic representation of the collective biomechanical and molecular mechanism of cell motion  [ 32 ]


3D rendering of centrioles showing the triplets


A mother and daughter centriole, attached  orthogonally


Electron micrograph of a centriole from a mouse embryo.


Neutrophils being repelled from a chemokinetic agent


Neutrophils are critical constituents of the innate immune system


Along the PIP3 gradient, the signaling pathway is highly conserved between  D.discoideum  and human neutrophils


Directional Decision Making Mechanism in a Human Neutrophil


Eukaryotic motile cilium


Illustration depicting motile cilia on  respiratory epithelium .


Tracheal  respiratory epithelium showing cilia and much smaller  microvilli  on non-ciliated cells in  scanning electron micrograph .


Scanning electron micrograph  of nodal cilia on a  mouse  embryo


Patterns of cancer cell invasion: collective cell and individual cell migration. In collective cell migration, tumor cells exhibit high expression of E-cadherin and integrins. Epithelial-mesenchymal (EMT) and collective-amoeboid (CAT) transitions are a trigger between collective cell invasion and individual cell migration. EMT involves activation of  transcription factors , such as  TWIST1 ,  Snail ,  Slug ,  ZEB1 / 2 , a decrease in  E-cadherin  expression, and an increase in  protease  activity. During EMT, tumor cells acquire the mesenchymal phenotype, detach from the tumor mass, and migrate by the mesenchymal mechanism. In contrast, the partial EMT that is specific to the tumor invasive front means that tumor cells retain cell-cell adhesion but already possess migratory ability. This tumor cell phenotype was named the “epithelial-mesenchymal” phenotype. In CAT, which takes place when  β1 integrins  are down-regulated, tumor cells detach from the tumor mass and move by the  amoeboid mechanism . Amoeboid migration involves a decrease in protease and integrin expression and changes in the activity of  GTPases  – inhibition of  Rac1  and activation of  RhoA . This movement type occurs in the loose/soft extracellular matrix. In contrast, mesenchymal migration is associated with the opposite phenotype and predominates in the dense/stiff matrix. These two movement types are highly plastic and can convert to each other, depending on the extracellular matrix type and intracellular regulation. [ 1 ]


This electron micrograph shows exaggerated filopodia with club-like shape induced by formin mDia2 in cultured cells. These filopodia are filled with bundled  actin filaments  which were born in and converged from the  lamellipodial network .


Prokaryotic  (bacterial and archaeal) flagella run in a rotary movement, while eukaryotic flagella run in a bending movement. The prokaryotic flagellum uses a  rotary motor , and the eukaryotic flagellum uses a complex sliding filament system. Eukaryotic flagella are ATP-driven, while prokaryotic flagella can be ATP-driven (Archaea) or proton-driven (Bacteria). [ 11 ]


Bacterial flagellar motor assembly: Shown here is the C-ring at the base with FliG in red, FliM in yellow, and FliN in shades of purple; the MS-ring in blue; the MotAB in brown; the LP-ring in pink; and the rod in gray. [ 25 ]


Eukaryotic flagella. 1–axoneme, 2–cell membrane, 3–IFT (IntraFlagellar Transport), 4–Basal body, 5–Cross section of flagella, 6–Triplets of microtubules of basal body


Cross section of an  axoneme


Longitudinal section through the flagella area in  Chlamydomonas reinhardtii . In the cell apex is the basal body that is the anchoring site for a flagellum. Basal bodies originate from and have a substructure similar to that of centrioles, with nine peripheral microtubule triplets (see structure at bottom center of image).


The "9+2" structure is visible in this cross-section micrograph of an axoneme.


Beating pattern of eukaryotic "flagellum" and "cillum", a traditional distinction before the structures of the two are known.


Immunofluorescence coloration of actin (green) and the focal adhesion protein vinculin (red) in a fibroblast. Focal adhesions are visible as red dots at the end of the green bundles.


Figure 1. Lamellipodia are thin-like projections on the leading edge of a cell (Image A). It is a feature of motile cells such as endothelial cells, neurons, and immune cells. The lamellipodia on the leading edge of the cell (green arrows) contain ATP- bound actin and the lamella on the "spike" end of the cell contain ADP-bound actin (red arrow). This allows for a "treadmilling" action to occur when the cell is signaled to move (Image B).  [ 3 ]


A  ribosome  is a  biological machine  that utilizes  protein dynamics


Kinesin   uses  protein domain dynamics  on  nanoscales  to walk along a  microtubule .


Molecular dynamics simulation of a  synthetic molecular motor  composed of three molecules in a nanopore (outer diameter 6.7 nm) at 250 K. [ 4 ]


Cell division.  All cells can be considered motile for having the ability to divide into two new daughter cells. [ 1 ]


Kinesin  "walking" on a  microtubule  using  protein dynamics  on  nanoscales


The action of myosin along the actin filaments causes the shortening and lengthening of the sarcomere; responsible for muscle contraction and relaxation, respectively.


Muscle fiber showing thick and thin myofilaments of a  myofibril .


Amoeba proteus  extending lobose pseudopodia


The forms of pseudopodia, from left: polypodial and lobose; monopodial and lobose; filose; conical; reticulose; tapering actinopods; non-tapering actinopods


The  radial spoke  shown in an  axoneme  cross-section


Muscle contraction based on  sliding filament theory


Molecular model of the Sarcomere in the A-band. Organization of the central region of the A-band (C-zone). The thin filaments (actin in green, tropomyosin in pink) and the thick filaments (myosins in the OFF state are depicted in shades of blue, titin in red) are densely packed within the sarcomere. The myosin-binding protein C (yellow) connects thick and thin filaments. Artistic representation based on publicly available models  [ 4 ] .


Cardiac sarcomere structure


Sliding filament theory: A  sarcomere  in relaxed (above) and contracted (below) positions


This model shows the four main and significant steps of the sliding filament theory as well as with a detailed visual.


Structure of muscle fibre (sarcomere) under electron microscope with schematic explanation


Diagrammatic explanation of sliding filament hypothesis


Actin Treadmilling Mechanism. This figure assumes that the critical  concentration  at the positive end is less than the critical concentration at the negative end and that the cytosolic subunit concentration is in between the positive and negative end critical concentrations.


Twitching motility. Type IV pili are extended from the surface of twitching-capable cells and attach to a nearby surface. Pilus retraction results in the forwards movement of the cell. Arrows indicate direction of pilus retraction/extension. Inset: Structure of the type IV pilus machinery. The four composing subcomplexes (the motor subcomplex (red), alignment subcomplex (blue and violet), secretion subcomplex (yellow) and pilus (green)) are highlighted.


The tug-of-war model of twitching motility. Cells (such as the shown  N. gonorrhoeae   diplococcus ) extend pili (green) that attach themselves to locations in the surrounding environment (blue circles). Pili experience tension due to activation of the retraction machinery. Upon detachment or rupture of a pilus (red), the cell quickly jerks into a new position based on the resulting balance of forces acting through the remaining pili.


Optical Scheme of 4Pi Microscope


Flow cytometry  using 7-AAD, wherein a lower signal indicates viable cells. Therefore, this case shows good viability.


Three brainbows of mouse neurons from Lichtman and Sanes, 2008


A brainbow of mouse neurons from Smith, 2007


Three copies of the genetic construct allow for the expression of multiple fluorophore color combinations. Lawson Kurtz et al. / Duke University


The basic Brainbow1 genetic construct. Lawson Kurtz et al. / Duke University


A brainbow of neurons in a mouse embryo (b), as well as some  tractographical  images of similar neurons (Chédotal and Richards, 2010)


Schematic of a typical setup for calcium fluorescence imaging of isolated cardiac myocytes


An example of cellomics software interface.


Confocal point sensor principle from Minsky's patent


GFP  fusion protein being expressed in  Nicotiana benthamiana . The fluorescence is visible by confocal microscopy.


This projection of multiple confocal images, taken at the  EMBL  light microscopy facility, shows a group of  diatoms  with cyan cell walls, red chloroplasts, blue DNA, and green membranes and organelles


Example of a stack of confocal microscope images showing the distribution of actin filaments throughout a cell.


Scheme from Minsky's patent application showing the principle of the transmission confocal scanning microscope he built.


Scheme of Petráň's Tandem-Scanning-Microscope. Red bar added to indicate the Nipkow-Disk.


Chemical-etching measured in real-time


Figure 1.  DHM phase shift image of cell details.


Surface finish measurement


Figure 2.  Typical optical setup of DHM.


Figure 3.  Comparison of a DHM phase shift image (left) and a  phase-contrast microscopy  image (right).


Figure 4.  DHM phase shift image of human  red blood cells .


Figure 5.  Time-lapse of unstained, dividing and migrating cells.


Self-healing surface recovering from a scratch : real-time measurement


Ultrasonic Transducers measured at 8 MHz in stroboscopic mode


Automatic measurement of hip prosthesis : surface roughness characterization


These are the colored Becke` lines of a glass sphere that matches the refractive index of the mounting medium at a wavelength of 589 nanometers.


Chart 1: These are the dispersion staining colors associated with different matching wavelengths when using any of the methods that generate a color pair.


This is the color shown by a glass sphere that matches the refractive index of the mounting medium at a wavelength of 589 nanometers when using darkfield dispersion staining.


Chart 2: These are the dispersion staining colors associated with different λo's when using any of the methods that generate a single color.


These are the colors shown by a glass sphere that matches the refractive index of the mounting medium at a wavelength of 589 nanometers when using phase contrast dispersion staining.


Multicolor fluorescence image of living HeLa cells


Diagram showing connection between absorption and fluorescence


Green fluorescent protein (GFP) being illuminated under UV light in three laboratory mice


Agarose gel using ethidium bromide as fluorescent tag under UV light illumination


Example of fluorescence microscope with a charged-coupled device (CCD) to capture images


Varying colors of fluorescence from range of fluorescent proteins


An upright fluorescence microscope (Olympus BX61) with the fluorescence filter cube turret above the objective lenses, coupled with a digital camera


Schematic of a fluorescence microscope


A sample of  herring   sperm  stained with  SYBR green  in a  cuvette  illuminated by blue light in an epifluorescence microscope. The SYBR green in the sample binds to the herring sperm  DNA  and, once bound, fluoresces giving off green light when illuminated by blue light.


Principle of FRAP A) The bilayer is uniformly labeled with a fluorescent tag B) This label is selectively photobleached by a small (~30 micrometre) fast light pulse C) The intensity within this bleached area is monitored as the bleached dye diffuses out and new dye diffuses in D) Eventually uniform intensity is restored


Typical core-domain of an FbFP ( PDB :  2PR5 )


Typical excitation and emission spectrum of FMN-binding fluorescent proteins (FbFPs)


Jablonski diagram  of FRET with typical timescales indicated. The black dashed line indicates a  virtual photon .


Cartoon diagram of the concept of Förster resonance energy transfer (FRET).


If the linker is intact, excitation at the absorbance wavelength of CFP (414 nm) causes emission by YFP (525 nm) due to FRET. If the linker is cleaved by a protease, FRET is abolished and emission is at the CFP wavelength (475 nm).


FRET-based probe that activates upon interaction with Cd2+


GCaMP bound to Ca 2+  (top) and unbound (bottom)


Aequorea victoria


3D reconstruction of confocal image of VEGF-overexpressing neural progenitors (red) and GFP-positive control neural progenitor cells (green) in the rat olfactory bulb. RECA-1-positive blood vessels - blue color.


The diversity of genetic mutations is illustrated by this San Diego beach scene drawn with living bacteria expressing 8 different colors of fluorescent proteins (derived from GFP and dsRed).


A palette of variants of GFP and DsRed.


Live lancelet ( B. floridae ) under a fluorescent microscope.


In the marine copepod  Pontella   mimocerami


Different proteins produce different fluorescent colors when exposed to ultraviolet light.


White light image, or image seen by the eye, of fluorescent proteins in image above.


E. coli colonies expressing fluorescent proteins.


Superresolution with two  fusion proteins  (GFP-Snf2H and RFP-H2A), Co-localisation studies (2CLM) in the nucleus of a bone cancer cell. 120.000 localized molecules in a widefield area (470 μm 2 ).


Mice expressing GFP under UV light (left & right), compared to normal mouse (center)


Julian Voss-Andreae 's GFP-based sculpture  Steel Jellyfish  (2006). The image shows the stainless-steel sculpture at  Friday Harbor Laboratories  on  San Juan Island  (Wash., USA), the place of GFP's discovery.


Eukaryote cells sort misfolded proteins into two quality control compartments: JUNQ and IPOD, based on their ubiquitination state.


Eukaryote cells sort misfolded proteins, based on their ubiquitination state, into two quality control compartments:  1. JUNQ (green), which is tethered to the  nucleus  (orange) 2. IPOD(green), which is tethered to the  vacuole  (black shadow)


A JUNQ inclusion viewed by a ubiquitinated VHL protein(green), is tethered to the  nucleus  (orange).


An IPOD inclusion viewed by a non-ubiquitinated VHL protein(red), tethered to the  vacuole  (green).


Laser capture micro-dissection transfer of pure  breast duct  epithelial cells. Left panel shows tissue section with selected cells removed. Right panel shows isolated epithelial cells on transfer film.


Laser Capture Microdissection


(partial) Optical path of a lattice light sheet microscope.  (a). from the laser lines and the AOTF,  (b). x cylindrical lens,  (c). z cylindrical lens,  (d). SLM,  (e). annulus mask,  (f). z and x galvos.,  (g). excitation objective,  (h). observation objective, (i). to EMCCD camera. inset: zoom on the objectives.


Lattice of destructively interfering Bessel beams. (a). schematic of destructive (top) and constructive (bottom) interference patterns between two Bessel beams. Note how the rings between the two centers get attenuated/amplified.  (b). interference pattern on a 2D optical lattice created by the interference of Bessel beams. inset: one Bessel function before interference,  (c)-left: SLM-mediated selection of a subpattern of the lattice, red: SLM pixels off, -right: view of the incident beam at sample (after dithering the beam in the x direction),  (d). Bessel function (left) and its intensity in the Fourier domain (right), and a zoom on the annulus (inset), (e). intensity at the Fourier plane of an array of Bessel beams (left) and its intensity at the object plane (right).


The principle setup of a light sheet fluorescence microscope.


Comparison of different microscopy illumination modalities (LSFM: light sheet fluorescence microscopy, WF: widefield microscopy, CF: confocal microscopy). Light sheet fluorescence microscopy combines good z-sectioning (as confocal) and illuminates only the observed plane


Illustration of different light sheet fluorescence microscope implementations. See text for details. Legend:  CAM=camera, TL=tube lens, F=filter, DO=detection objective, S=sample, SC=sample chamber, PO=projection objective, CL=cylindrical lens, SM=scanning mirror


Different types of sample mounting for light sheet fluorescence microscopy: embryo embedded in hanging gel cylinder, plant growing in supported gel cylinder, adherent cells on glass, liquid sample in a sample bag


Top: stripe artifacts in light sheet fluorescence microscopy. Bottom: Reducing stripe artifacts by pivoting


A live-cell microscope. Live-cell microscopes are generally  inverted . To keep cells alive during observation, the microscopes are commonly enclosed in a micro  cell incubator  (the transparent box).


A) Upright lens configuration. B) Inverted lens configuration.


Scanning electron microscope  image of  pollen  (false colors)


Microscopic examination in a biochemical laboratory


Antonie van Leeuwenhoek  (1632–1723)


Stereo microscope


A  diatom  under Rheinberg illumination


Phase-contrast  light micrograph  of undecalcified  hyaline cartilage  showing  chondrocytes  and  organelles ,  lacunae  and  extracellular matrix


Images may also contain  artifacts . This is a  confocal laser scanning   fluorescence   micrograph  of  thale cress  anther (part of  stamen ). The picture shows among other things a nice red flowing collar-like structure just below the anther. However, an intact thale cress stamen does not have such collar, this is a fixation artifact: the stamen has been cut below the picture frame, and  epidermis  (upper layer of cells) of stamen stalk has peeled off, forming a non-characteristic structure. Photo: Heiti Paves from  Tallinn University of Technology .


Mathematically modeled Point Spread Function of a pulsed THz laser imaging system. [ 31 ]


Example of super-resolution microscopy. Image of  Her3  and  Her2 , target of the  breast cancer  drug  Trastuzumab , within a cancer cell.


Human cells imaged by DHM phase shift (left) and  phase contrast microscopy  (right)


Photoacoustic micrograph of human red blood cells.


The schematic of a multifocal plane microscope


A comparison of the depth discrimination of MUM with conventional single plane microscopy


Dual objective multifocal plane microscope (dMUM)


Diagram illustrating  near-field optics , with the diffraction of light coming from NSOM fiber probe, showing wavelength of light and the near-field. [ 1 ]


Comparison of photoluminescence maps recorded from a  molybdenum disulfide  flake using NSOM with a  campanile probe  (top) and conventional  confocal microscopy  (bottom). Scale bars: 1 μm. [ 2 ]


Sketch of a) typical metal-coated tip, and b) sharp uncoated tip. [ 19 ]


Apertured modes of operation: a) illumination, b) collection, c) illumination collection, d) reflection and e) reflection collection. [ 20 ]


Apertureless modes of operation: a) photon tunneling (PSTM) by a sharp transparent tip, b) PSTM by sharp opaque tip on smooth surface, and c) scanning interferometric apertureless microscopy with double modulation. [ 19 ]


Block diagram of an apertureless reflection-back-to-the-fiber NSOM setup with shear-force distance control and cross-polarization; 1:  beam splitter  and crossed polarizers; 2: shear-force arrangement; 3: sample mount on a piezo stage. [ 20 ]


Typical atomic force microscopy set-up


The same cells imaged with traditional bright-field microscopy (left), and with phase-contrast microscopy (right)


S. cerevisiae  cells imaged by  DIC microscopy


A  quantitative phase-contrast microscopy  image of cells in culture. The height and color of an image point correspond to the optical thickness, which only depends on the object's thickness and the relative  refractive index . The volume of an object can thus be determined when the difference in refractive index between the object and the surrounding media is known.


Vectorial representation of waves and their superposition.


Temporal phasor for decay curves with different lifetimes.


The intensity,phasor and lifetime image of cells stained with Alexa 488 and Alexa 555.


Reference semicircle for different gate configurations.


Behavior of the phasor for different spectral widths.


Behavior of the phasor for different emission maximum.


The linear property of phasor approach.


To find the fractional intensities, or the contribution from pure spectra, we need to find out the area that is made by connecting the phasor of the total spectrum, (shown by yellow phasor), to the phasor of pure spectra which are shown by (A1, A2, A3).


The intensity image, Phasor image and the unmixed results for a cell transfected with DAPI,BODIPY and texas red shown by blue, green and red respectively.


Multiple closely spaced emitters are indistinguishable. The position of a point source can be recovered only if the photons it emitted have been identified from those arising from the neighboring molecules


Photoactivation, localization and bleaching


Single CCD frame displaying individual fluorescent proteins excited in Total Internal Reflection


Sequence of frames containing single molecule images


Self-organization of the  Escherichia coli  chemotaxis network imaged with super-resolution light microscopy. Scale bar in (A–E) indicates 1 μm. Scale bar in (F–H) indicates 50 nm. [ 11 ]


Strategies for multicolor localization microscopy. Left: spectral separation. Center: multiple activators (STORM). Right: Ratiometric imaging


Pulse-chase analysis of  auxin  signal transduction in an  Arabidopsis thaliana  wildtype and an axr2-1 mutant. Wild-type and axr2-1 seedlings were labeled with 35S- methionine , and AXR2/axr2-1 protein was  immunoprecipitated  either immediately after the labeling period (t = 0) or following a 15-minute chase with unlabeled methionine (t = 15).


Figure 1 : In this phase shift image of cells in culture, the height and color of an image point correspond to the measured phase shift. The phase shift induced by an object in an image point depends only on the object thickness and the relative  refractive index  of the object in the image point. The volume of an object can therefore be determined from a phase shift image when the difference in refractive index between the object and the surrounding media is known. [ 3 ]


Confocal Raman imaging microscope


Raman microscope


Chemical image of a pharmaceutical emulsion acquired by confocal Raman microscopy (alpha300 microscope, WITec; blue: Active pharmaceutical ingredient, green: Oil, red: Silicon impurities).


Correlative Raman-SEM imaging of a hematite (taken with RISE microscope, WITec). The Raman image is overlaid over the SEM image.


Second-harmonic image of collagen (shown in white) in liver


Biological tissues imaged by second-harmonic generation (SHG) microscopy. (a) Transverse cut of a human cornea. (b) Skeletal muscle from zebrafish (myosin). (c) Adult mice-tail tendon. (d) Surface cartilage from a knee of a mature horse.


The SELEX method.


Crystal structure of Spinach PDB: 4KZD  [1]


Stimulated emission depletion (STED) microscopy provides significant resolution improvements over those possible with  Confocal microscopy .


Ernst Abbe's formula for the diffraction limit, set in stone at a monument in  Jena .


Jablonski diagram showing the redshift of the stimulated photon. This redshift allows the stimulated photon to be ignored.


Diagram of the design of a STED device. The double laser design allows for excitation and stimulated emission to be used together for STED.


Comparison of confocal microscopy and STED microscopy. This shows the improved resolution of STED microscopy over traditional techniques.


Excitation spot (2D, left), doughnut-shape de-excitation spot (center) and remaining area allowing fluorescence (right).


Comparison of the resolution obtained by  confocal laser scanning microscopy  (top) and 3D structured illumination microscopy (3D-SIM-Microscopy, bottom). Shown are details of a  nuclear envelope . Nuclear pores (anti-NPC) red, nuclear envelope (anti- Lamin ) green,  chromatin  ( DAPI -staining) blue. Scale bar: 1 μm.


SMI +  TIRF  of human eye tissue affected by  macular degeneration


Resolution improvement between traditional confocal microscopy and STED microscopy.


Single YFP molecule super resolution microscopy / SPDMphymod


Dual color localization microscopy SPDMphymod/super-resolution microscopy with GFP & RFP fusion proteins


Cryogenic Optical Localization in Three Dimensions (COLD) allows to determine the four biotin binding sites in the protein streptavidin.


fBALM Super-resolution single molecule localisation microscopy using DNA structure fluctuation assisted binding activated localisation microscopy


Label-free Localisation Microscopy SPDM – Super Resolution Microscopy reveals prior undetectable intracellular structures


3D Dual Colour Super Resolution Microscopy with Her2 and Her3 in breast cells, standard dyes: Alexa 488, Alexa 568 LIMON


One of the microcinematographs used at the Marey Institute during the late 19th century


(Trans-)total internal reflection fluorescence microscope (TIRFM) diagram  Objective Emission beam (signal) Immersion oil Cover slip Specimen Evanescent wave range Excitation beam Quartz prism


(Cis-) total internal reflection fluorescence microscope  (TIRFM) diagram  Specimen Evanescent wave range Cover slip Immersion oil Objective Emission beam (signal) Excitation beam


Two-photon excitation microscopy of mouse  intestine . Red:  actin . Green:  cell nuclei . Blue: mucus of  goblet cells . Obtained at 780 nm using a  Ti-sapphire laser .


Two-photon fluorescence image (green) of a cross section of  rhizome  colored with  lily of the valley . The excitement is at 840 nm, and the red and blue colors represent other channels of multiphoton techniques which have been superimposed.


Schematic representation of the energy levels (Jabłoński diagrams) of the fluorescence process, example of a fluorescent dye that emits light at 460 nm. One (purple, 1PEF), two (light red, 2PEF) or three (dark red, 3PEF) photons are absorbed to emit a photon of fluorescence (turquoise).


Optical response from a point source. From left to right: calculated intensity distributions xy (top) and rz (bottom), with logarithmic scale, for a point source imaged by means of a wide field (a), 2PEF (b) and confocal microscopy (c). The 2PEF and confocal forms have a better signal-to-noise ratio than the wide field. The 2PEF distribution is larger due to the fact that a wavelength twice as long as in the case of a wide or confocal field is responsible for the intensity distribution. These intensity distributions are also known as point spread functions. Optical conditions: the excitation wavelengths are 488 nm and 900 nm respectively for 1PEF and 2PEF; the emission wavelength is 520 nm; the  numerical aperture  is 1.3 with an  oil immersion objective .


A diagram of a two-photon microscope.


Diagram of in vivo brain function imaging. Shows the general schematic for imaging, along with neuronal and vascular images. Imaging was performed using various fluorescent dyes.


Heteronuclear NMR techniques in carbohydrate studies, and typical intra-residue (red) and inter-residue (blue) atoms that they link each to other.


Homonuclear NMR techniques in carbohydrate studies, and typical intra-residue (red) and inter-residue (blue) atoms that they link each to other.


Approximate scheme of NMR (blue) and other (green) techniques applied to carbohydrate structure elucidation, and information obtained (in boxes)


Comparative prediction of the 13C NMR spectrum of sucrose using various methods. Experimental spectrum is in the middle. Upper spectrum (black) was obtained by empirical routine. Lower spectra (red and green) were obtained by quantum-chemical calculations in PRIRODA and GAUSSIAN respectively. Included information: used theory level/basis set/solvent model, accuracy of prediction (linear correlation factor and root mean square deviation), calculation time on personal computer (blue).


Catabolism of  proteinogenic amino acids . Amino acids are classified according to the abilities of their products to enter gluconeogenesis: [ 7 ]   Glucogenic amino acids  have this ability Ketogenic amino acids  do not. These products may still be used for  ketogenesis  or  lipid synthesis . Some amino acids are catabolized into both glucogenic and ketogenic products.


Gluconeogenesis pathway with key molecules and enzymes. Many steps are the opposite of those found in the  glycolysis .


Spike (S) protein  responsible for the binding to ACE2 receptors in COVID-19. Glycans highlighted in blue. Structure taken from PDB entry 6VXX [ 1 ]


Figure 1.  The schematic representation of

 C
 H
 −
 π

 {\displaystyle CH-\pi }

  interactions


The definition of alpha and beta faces for glucose and galactose. The stereochemical difference for two hexoses is highlighted in red.


Figure 2.  Electrostatic Surface Potentials (ESPs) of aromatic amino acids. Electron rich areas are depicted with red, while electron poor areas are depicted with blue.


Crystal Structure of VLRB.aGPA.23 created from PDB Entry 4K79 [ 12 ]


Cartoon depiction of common oligomeric structures of lectins


Overview of several types of N-Glycans that can vary on different HIV strains.


Mannose-6-Phosphate (left) and Sialic Acid (right) are common saccharides that are found on glycosylated residues.


2D chemical structure of Zanamivir.


The glycocalyx exists in bacteria as either a capsule or a slime layer. Item 6 points at the glycocalyx. The difference between a capsule and a slime layer is that in a capsule polysaccharides are firmly attached to the cell wall, while in a slime layer, the glycoproteins are loosely attached to the cell wall.


Schematic two-dimensional cross-sectional view of glycogen: A core protein of  glycogenin  is surrounded by branches of  glucose  units. The entire globular granule may contain around 30,000 glucose units. [ 1 ]


A view of the  atomic  structure of a single branched strand of  glucose  units in a glycogen  molecule .


Glycogen (black granules) in  spermatozoa  of a  flatworm ;  transmission electron microscopy , scale: 0.3 μm


α(1→4)-glycosidic linkages in the glycogen oligomer


α(1→4)-glycosidic and α(1→6)-glycosidic linkages in the glycogen oligomer


Metabolism of common monosaccharides


Action of glycogen phosphorylase on glycogen


GYG-1 gene location in chromosome 3.


A Pancreatic  alpha-Amylase  1HNY, a  glycoside hydrolase


Most glycosyltransferase enzymes form one of two folds: GT-A or GT-B


Mutant endomannase with bound mannodiose, 1ODZ, [ 1 ]  a  glycosynthase


National Center for Functional Glycomics (NCFG)


Neuraminidase (GH34)  ribbon diagram . An analog of its neuraminic acid substrate, used as an inhibitor drug, is the small white and red molecule in the center.


N-Acetylneuraminic acid


Protein paucimannosylation. The common trimannosylchitobiose core derivatised with an α1,6-linked core fucosylation (M3F) forming one of the largest structures of the paucimannosidic glycan series is represented as A) the standardised symbol nomenclature for glycans,. [ 1 ]  and B-C) sticks and space fill glycan, respectively, conjugated to an asparagine residue (Asn) on the surface of a protein carrier (turquoise). Monosaccharide color code: Red: fucose, Blue: N-acetylglucosamine, Green: mannose.


Peptidoglycan.


Cell culture in a small  Petri dish


Epithelial cells  in culture,  stained  for  keratin  (red) and  DNA  (green)


Cultured cells growing in  growth medium


A bottle of DMEM cell culture medium


Cultured  HeLa  cells have been stained with  Hoechst  turning their  nuclei  blue, and are one of the earliest human cell lines descended from  Henrietta Lacks , who died of cervical cancer from which these cells originated.


Schematic representation of 2D culture, 3D culture, organ-on-a-chip and in vivo study


Nanofibrillar cellulose hydrogel


SEM image of NFC network


NFC hydrogel and cell culture medium in 384-well plate


Capsaspora owczarzaki adherent cells visualized using fluorescence microscopy.


Pseudostratified epithelium of the trachea ALI cell culture aims to recreate  in vitro


Nicotiana tabacum  parenchyma cells in culture


Callus cells forming during a process called "induction" in  Pteris vittata


Callus induced from  Pteris vittata  gametophytes


3D cell culture grown with MLM. Human  Glioblastoma  (HGBM) cells (indicated by the lower arrow) treated with magnetic nanoparticles were held at the air-medium interface by the magnetic field created by the magnet attached to the top of the first tissue culture plate. This image was taken after 48 hours of culturing.


Process demonstrating 3D cell culturing through magnetic levitation with a cell culturing system, split into five phases (A to E).(A) A magnetic iron oxide nanoparticle assembly, known as the "nanoshuttle", is added and dispersed over cells, and the mixture is incubated.   (B) After incubation with the nanoshuttle, the cells are detached and transferred to a petri dish.   (C) A magnetic drive is then placed on top of a petri dish.   (D) The magnetic field causes cells to rise to the air–medium interface.   (E) Human umbilical vein endothelial cells (HUVEC) levitated for 60 minutes (left two images in E) and 4 hours (right two images in E) (scale bar: 50 μm).


Distribution of N-cadherin (red) and  nuclei  (blue). [ 2 ]  Left: human brain cancer cells grown in a  mouse brain  (xenograft). Middle: brain cancer cells cultured by 3D magnetic levitation for 48 hours. Right: cells cultured on a 2D glass slide cover slip.


An invasion assay of magnetically levitated multicellular spheroids. [ 2 ]  Fluorescence images of human GBM cells (green;  GFP -expressing cells) and NHA (red;  MCherry -labelled), cultured separately then magnetically guided together.


Organized bronchiole created with a 3D cell culturing system and cell manipulation tool. Scale bar: 100um.


Adipocytes cultured by MLM acquire in-vivo morphology in adipospheres. [ 6 ]


Hepatoma cultured by MLM for different cell numbers at 24 hours.


Primary pulmonary fibroblasts cultured by MLM compared to in-vivo. [ 7 ]


Primary small airway epithelial cells cultured by MLM compared to in-vivo. [ 7 ]


Human alveolar adenocarcinoma cell line -  A549  cultured by MLM at different time points and cell numbers. [ 7 ]


Immunohistochemistry  (IHC) reveals epithelial markers on A549 after culturing in 3D with the MLM.


HTSMCs cultured by MLM with IHC staining. [ 7 ]


HMSCs cultured by MLM.


Dental pulp  cultured by MLM (3D vs. 2D) - 5 days.


HUVECs cultured by MLM in 24 Well format.


Chondrocytes  cultured in 3D by MLM at different time points.


Primary WAT cells cultured by MLM assemble into vascularized adipospheres. [ 6 ]


Levitating neural stem cells cultured by MLM.


HEK 293  cultured by MLM and tested with  ibuprofen  using bioassay.


Astrocyte and glioblastoma invasion assay performed after 3D culturing by MLM. [ 2 ]


Glioblastoma cultured with Bio-Assembler vs. Matrigel at 24 hours. [ 2 ]


Bio-Assembler vs. Matrigel with human mammary epithelial cells.


Microbial cultures on solid and liquid media


A culture of  Bacillus anthracis


Liquid cultures of the  cyanobacterium   Synechococcus  PCC 7002


Example of a workup algorithm of possible bacterial infection in cases with no specifically requested targets (non-bacteria, mycobacteria etc.), with most common situations and agents seen in a New England setting. The grey box near top left shows a  Venn diagram  of what culture media are routinely used for various sources or purposes.


Motile and non-motile bacteria can be differentiated along the stab lines. Motile bacteria (left) will grow out from the stab line while non-motile bacteria (right) are present only along the stab line.


Figure 1: Mounting of a Minusheet tissue carrier. (a) First an individual biomaterial measuring 13 mm in diameter is selected. (b) For mounting the biomaterial is placed in the base part of a tissue carrier. (c) After pressing down a tension ring the mounted tissue carrier can be used for cell seeding. For improved provision with medium a tissue carrier rests with protrusions at the bottom of a dish.


Figure 2: Minusheet tissue carriers including different biomaterials within a 24 well culture plate. Cell seeding is performed in static environment of this dish.


Figure 3: Variety of perfusion culture containers for insertion of Minusheet tissue carriers.


Figure 4: Use of a Minusheet tissue carrier in perfusion culture containers. (a) A standard perfusion culture container holds six tissue carriers to provide them with always fresh medium. (b) In a gradient perfusion culture container an epithelium is exposed to different fluids at the luminal and basal side. (c) In a microscope container a transparent lid and base allow observation of developing tissue during perfusion culture.


Figure 5: Perfusion culture set-up is working on a laboratory table. A thermo plate maintains the desired temperature of 37°C. During culture a peristaltic pump transports the medium for example with 1.25 mL/h from a storage bottle (left side) to the waste bottle (right side).


Figure 6: Gas exchange and gas expander module for perfusion culture. (a) A gas exchange module is used, when adaption of respiratory gas in perfusion culture has to be performed. By a gas inlet and outlet the desired gas composition is transported to a spiral of silicone tube containing the culture medium. Between the wall of the silicone tube gas is exchanged. (b) A gas expander module is used for the elimination of gas bubbles during transport of culture medium. Medium with gas bubbles is entering at the inlet and has to pass a barrier. Here the medium expands and bubbles are separated. Finally medium is leaving the container bubble-free but gas-saturated.


Figure 7: Perfusion culture set-up with an epithelium inside a gradient perfusion culture container. A thermo plate maintains the desired temperature of 37°C. To provide the luminal and basal side of the contained epithelium with nutrition and respiratory gas, two channels of a peristaltic pump transport a red and a clear medium at exactly the same rate of 1.25 mL/h from a storage bottle (left side) to the waste bottle (right side). For elimination of gas bubbles during transport of medium a gas expander module is placed before the gradient container.


Figure 3: This diagram shows three techniques used in in-vitro culture of ovarian tissue; culture of ovarian fragments in a floating organ culture system, individual follicle culture of enzymatically digested/ minced ovarian follicles, and perfusion whole ovary in a flow-through system. [ 2 ]


The NASA bioreactor provides a low turbulence environment, promoting the formation of large, three-dimensional cell clusters. Credit: NASA


Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Credit: NASA


Switchgrass  somatic embryos


Roughly 100,000 cells from rhesus macaques, grouped by similarity. Each colour highlights cells from a different tissue, e.g. thymus and lymph nodes (shades of blue), bone marrow (red), blood (white), tonsil (yellow), gut (shades of brown), brain (grey), liver (green), spleen (purple) and lung (pink).


Flasks containing tissue culture  growth medium  which provides nourishment for the growing of cells.


Cultured cells growing in  growth medium


Kari K. Alitalo in 2014. (Jussi Puikkonen / KNAW)


Ryerson University Dean of Science, Professor Imogen Coe


Imogen Coe at Soapbox Science Toronto May 2017


Laurent Degos


Desh Verma in 2021.


Steven Novella ,  Harriet Hall ,  David Gorski , and Rachael Dunlop (right) on a panel at  The Amaz!ng Meeting  2012


Erdmann (left) in her Berlin laboratory, 1929


Rhoda Erdmann in the 1930s


Clip from the front page of The Ogden Standard (newspaper), Ogden City, Utah on Wednesday May 15, 1918


Dame Anne Glover


Chief Scientific Adviser to the  European Commission , Anne Glover, visits  ESO 's  Paranal Observatory . [ 15 ]


Lydia and Anna Gurwitsch


Ulf Kahlert


La Cour in 1972


Grigory Levitsky


Drosophila melanogaster under microscope


A simplified diagram of the initiation of the UPR by prolonged and overwhelming protein misfolding


Plácido Navas Lloret in Bologna


Ohsumi addressed at  Gairdner Foundation International Award  Ceremony (at the  Royal Ontario Museum  in October 2015)


with  John Dirks , Kenjirō Monji and  D. Lorne Tyrrell


Ohsumi in his Tokyo Tech lab


Palade on a 2016 Romanian stamp


Illustration of how cells sense and adapt to oxygen availability


Moss bioreactor  with  Physcomitrella patens


Professor Sonia Rocha


Gesammelte Abhandlungen über Entwickelungsmechanik der Organismen , 1895


Sandra L. Schmid, Cell Biologist


Fluorescence microscopy time series of a dividing cell, illustrating that the Sox2 transcription factor is retained on mitotic chromosomes. They also found that  SOX2  plays a key role in maintaining cell identity during the transition from mitosis to interphase. [ 12 ]


Dimitrie Voinov


Theo Wallimann , a Swiss  biologist


Copy of Dedication page to Plant Cell Biology sent to Thomas Chargaff, son of Erwin Chargaff


Shinya Yamanaka speaking at a lecture on 2010 January 14


Yamanaka and  Ryōji Noyori  participating in the ceremony of the  50th All Japan Rugby Football Championship


Yanagida received the  Order of Culture . After that, they posed for the photo. (at the East Garden of the  Tokyo Imperial Palace  on November 3, 2011)


Principal interactions of structural proteins at cadherin-based adherens junction. Actin filaments are associated with adherens junctions in addition to several other actin-binding proteins such as  vinculin . The head domain of vinculin associates to E-cadherin via α-, β - and γ -catenins. The tail domain of vinculin binds to membrane lipids and to actin filaments.


Amyloplasts in a potato cell


A diagram showing the different types of plastid


Diagram of a  voltage-gated ion channel , showing the three states: closed, open, and inactivated. Ball and chain inactivation can only happen if the channel is open.


Diagram of a  voltage-gated sodium channel , showing the important residues for inactivation in red. The domain structure (I – IV) is further subdivided into segments (S1 – 6). The S4 segment is the voltage sensor, which moves out during  depolarisation  of the  cell membrane . This frees up the  alanine  and  asparagine  residues with which the IFMT residues in the ball domain bind to. Adapted from Goldin, 2003. [ 13 ]


Nuclei of mouse cells (blue) containing Cajal bodies (green) visualized by fusion of p80/Coilin protein to GFP


Electron micrographs showing alpha-carboxysomes from the chemoautotrophic bacterium  Halothiobacillus neapolitanus : (A) arranged within the cell, and (B) intact upon isolation. Scale bars indicate 100 nm. [ 1 ]


Model for the structure of the carboxysome. RuBisCO and carbonic anhydrase are arranged in an enzymatic core (organized by various core proteins) and encapsulated by a protein shell.


Electron micrograph of (A) alpha-carboxysomes in  Halothiobacillus neapolitanus  and (B) beta-carboxysomes in  Synechococcus elongatus  PCC 7942, indicated by arrows. Scale bars 200 nm.


Structure of a typical  prokaryotic  cell


Structure of a typical animal cell


Structure of a typical  plant cell


Detailed diagram of lipid bilayer of cell membrane


A fluorescent image of an endothelial cell. Nuclei are stained blue,  mitochondria  are stained red, and microfilaments are stained green.


Deoxyribonucleic acid  (DNA)


Human cancer cells, specifically  HeLa cells , with DNA stained blue. The central and rightmost cell are in  interphase , so their DNA is diffuse and the entire nuclei are labelled. The cell on the left is going through  mitosis  and its chromosomes have condensed.


Diagram of the  endomembrane system


Prokaryotes  divide by  binary fission , while  eukaryotes  divide by  mitosis  or  meiosis .


Staining of a  Caenorhabditis elegans  highlights the nuclei of its cells.


Stromatolites  are left behind by  cyanobacteria , also called blue-green algae. They are among the oldest fossils of life on Earth. This one-billion-year-old fossil is from  Glacier National Park  in the United States.


In the theory of  symbiogenesis , a merger of an  archaean  and an aerobic bacterium created the eukaryotes, with aerobic  mitochondria , some 2.2 billion years ago. A second merger, 1.6 billion years ago, added  chloroplasts , creating the green plants. [ 31 ]


Robert Hooke's drawing of cells in  cork , 1665


Cartoon of the dividing epithelium cell surrounded by epithelium tissue. Spindle apparatus rotates inside the cell. The rotation is a result of astral microtubules pulling towards tri-cellular-junctions (TCJ), signaling centers localized at the regions where three cells meet.


Some examples of cell junctions


This image shows a desmosome junction between cells of the epidermal layer of the skin.


The cartoon of epithelium cells connected by tricellular junctions at the regions where three cells meet.


Illustration of a  eukaryotic  cell membrane


Comparison of a  eukaryotic  vs. a  prokaryotic  cell membrane


Examples of the major membrane phospholipids and glycolipids:  phosphatidylcholine  (PtdCho),  phosphatidylethanolamine  (PtdEtn),  phosphatidylinositol  (PtdIns),  phosphatidylserine  (PtdSer).


A detailed diagram of the cell membrane


Illustration depicting cellular diffusion


Diagram of the arrangement of amphipathic lipid molecules to form a  lipid bilayer . The yellow  polar  head groups separate the grey hydrophobic tails from the aqueous cytosolic and extracellular environments.


Alpha intercalated cell


Diagram of the cell membrane's structures


HeLa cells  stained for  nuclear DNA  with the blue  fluorescent   Hoechst dye . The central and rightmost cells are in  interphase , thus their entire nuclei are labeled. On the left, a cell is going through  mitosis  and its DNA has condensed.


A mouse  fibroblast  nucleus in which  DNA  is stained blue. The distinct chromosome territories of chromosome 2 (red) and chromosome 9 (green) are stained with  fluorescent in situ hybridization .


Diagram of the nucleus showing the  ribosome -studded  outer nuclear membrane ,  nuclear pores ,  DNA  (complexed as  chromatin ), and the  nucleolus .


A cross section of a  nuclear pore  on the surface of the  nuclear envelope  (1). Other diagram labels show (2) the outer ring, (3) spokes, (4) basket, and (5) filaments.


An  electron micrograph  of a cell nucleus, showing the darkly stained  nucleolus


Cajal body


A generic  transcription factory  during transcription, highlighting the possibility of transcribing more than one gene at a time. The diagram includes 8 RNA polymerases however the number can vary depending on cell type. The image also includes transcription factors and a porous, protein core.


Macromolecules , such as  RNA  and  proteins , are  actively transported  across the nuclear membrane in a process called the  Ran - GTP  nuclear transport cycle.


An image of a  newt   lung  cell  stained  with  fluorescent   dyes  during  metaphase . The  mitotic spindle  can be seen, stained green, attached to the two sets of  chromosomes , stained light blue. All chromosomes but one are already at the metaphase plate.


Human red blood cells, like those of other mammals, lack nuclei. This occurs as a normal part of the cells' development.


Oldest known depiction of cells and their nuclei by  Antonie van Leeuwenhoek , 1719


Drawing of a  Chironomus   salivary gland  cell published by  Walther Flemming  in 1882. The nucleus contains  polytene chromosomes .


Basic cellular compartments


An illustration of  podocytes , which surround the  glomerular capillaries  with their cell bodies, primary processes and interdigitating  foot processes .


Filopodia and lamellipodia in two fluorescently-labeled  growth cones .