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And it's such a regular pattern,
and they're all perfectly
there.
After listening to the
overexposure of sound,
there are quite a few
inner hair cells lost.
Those that are
remaining sometimes
have abnormal stereocilia.
There are number of outer
hair cells, in this case,
in row one lost.
And some that are remaining
are indicated by these arrows
to have abnormal stereocilia.
And here's another example
from a different place
in the cochlea where almost the
entire third row of outer hair
cells is wiped out by the
overexposure to noise.
So what happens when
you lose a hair cell?
Well, the nearby supporting
cells go fill in its space,
and they take over.
In mammals, such
damage is permanent.
Once the hair cell is
killed, it never grows back.
And there's a lot of
interest in trying
to coax the nearby
supporting cells
to, in these damage
cochleas, become hair cells.
But so far that has
not been possible.
The field was really
excited about 20 years ago
when this type of damage
in a bird cochlea,
if left for a month
or so, you see
reemerging small hair cells.
And if you wait long enough,
they become full hair cells.
In the bird cochlea, the
surrounding supporting cells,
after damage to the hair cells,
can then divide and become
new hair cells, in the
chicken cochlea, for example.
And this was a
serendipitous discovery
where people were working on
damaging chicken hair cells,
and they were always waiting a
couple days after the exposure
to look at the cochleas.
And there was a holiday vacation
where they exposed the animals
before, and they