Numbers of regenerating axons in parent and tributary peripheral nerves in the rat
Jenq, C.B.; Coggeshall, R.E.
Brain Research 326(1): 27-40
ISSN/ISBN: 0006-8993 PMID: 3971147 DOI: 10.1016/0006-8993(85)91381-2
Numerical parameters of axonal regeneration in peripheral nerves are considered. The number of axons that regenerate into the distal stump of a somatic nerve at a particular time after transection is partially dependent on the type of lesion used to interrupt the axons. The proportion of axons that regenerate into the distal stump of a parent nerve compared to the proportions that regenerate into tributary nerves that arise from the parent is examined. The proportions of regenerated myelinated axons in the nerve to the medial gastrocnemius muscle, and myelinated and unmyelinated axons in the sural nerve are the same as the proportions of myelinated and unmyelinated axons that regenerate into the distal stump of the sciatic nerve for the crush, 0 and 4 mm gap transections. Proportionally fewer axons regenerate into the tributary nerves following the 8 mm gap transection, however. This implies that the length of the gap has an influence on whether or not axons in tributary nerves regenerate in concert with axons in the distal stump of the parent nerve. The unmyelinated fibers in the nerve to the medial gastrocnemius muscle are different because they do not regenerate in proportion to those in the distal stump of the sciatic nerve. Evidence is provided to indicate that myelinated axons branch, whereas unmyelinated fibers end blindly when they enter the distal stump after crossing a sciatic nerve transection. The normal arrangement of perineurial cells seems to be disrupted after the sciatic nerve regenerates across a gap.