Quote:
Originally Posted by Mike F
Captain is right though - spinal cord researchers are making progress on regeneration, but getting a nerve to transverse a gap and connect with the correct end on the other side of the gap is an outstanding problem.
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A nerve is really a cord with a lot of neuron axons in it. When it is cut, the portion distal to the cell body will die (a nerve cell is a cell body with a very long axon). For example, neurons with their cell body in the brain may have an axon that extends all the way to down the spinal cord to motor neurons of the legs (one cell may be several feet long). If you cut that axon at the neck, the remaining axon will degrade/die because it does not have a cell body to support it. This means you cannot re-connect a cut neuron... you can sow together the outer sheath of the nerve, but you cannot sow together neurons inside of the nerve. They are just too small! Therefore the cut axon will degrade and will need to be replaced with a new one growing from the cell body.
Neurons do have the capacity to regrow their cut axons. After being cut, some neurons will re-grow to the correct destination, but others will not. To restore voluntary leg movements, you would need the re-growing axon to transverse the entire spinal cord, from cut region in the neck to the lumbo-sacral spinal cord region. The chances of that happening are not good.