Question:
Do nerve and muscle cells go through "regular"
mitosis? And if they do how long is the process? If nerve cells go
through mitosis, why do we have unrepaired nerve damage?
Replies:
Some cells are permanently arrested in G1 interphase once they are created
by mitosis. Most nerve cells fit this category. Actually when cells are
"stuck" in G1, we call this G0 (that should be a subscript zero). All
cells
sit in G1 until given the Go signal by a transcription factor or hormone,
or
some other cell signal. These are specific for the type of cell and where
it is in the body. For example, squamous epithelial cells in the cheek
have a very rapid cell cycle because they need to be replaced constantly.
However, nerve cells don't get the Go signal again once they have been
produced. Therefore, if they are lost, they don't get replaced.
Scientists are trying to figure out a way to get the body to make more from
stem cells.
They have had some success. The same applies to muscle cells.
Each cell can make more
fibers in its life time, which allows the muscle cells and therefore the
muscle to "pump up" during much use. When the exercise is discontinued,
the
extra fibers are broken down again and the muscles atrophy.
vanhoeck
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
