MadSci Network: Cell Biology

Re: How long do cone cells live?

Date: Mon Jan 28 12:04:39 2008
Posted By: Kenneth Mitton, Assistant Professor of Biomedical Sciences
Area of science: Cell Biology
ID: 1201462832.Cb

Cones cells, and also rod cells, are photoreceptor neurons of the neural

During development, before birth in humans, our neural retinas are formed
by a supply of cells called neural progenitor cells. These divide and
divide to make the number of cells you will need for your functional
retina. At some point most of these cells stop dividing and they "choose"
their cell fate. That is they start to differentiate into one of the six
major neurons of the retina: cones, rods, bipolar cells, amacrine cells,
horizontal cells or ganglion cells (ganglion cells have loooong axons that
bundle together to make your optic nerve and they stretch all the way to
your brain).

All of these cells are formed; turning into these different cell types with
different jobs. They do not divide again. Then, if your retina is healthy,
these cells last your entire life. Therefore, cone cells live as long as
you do.

That is why losing photoreceptors (cones and rods), due to diabetes effects
etc., is such a problem. You cannot grow new ones.

DR Ken Mitton, PhD
Associate Professor of Biomedical Research
Oakland University
Eye Research Institute
Rochester MI

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