Regeneration of a transected peripheral nerve. An autoradiographic and electron microscopic study.

The regeneration of transected peripheral nerves of mice was studied using autoradiographical and electron microscopical techniques. In general, maximal proliferation occurred between the 5th and 7th day after dissection and stopped when the cells emigrating from the proximal and distal stumps of the nerve started to contact one another. Special attention was paid to the reaction of the connective tissue cells of the endo-, epi- and perineurium. The perineurial cells seemed to dedifferentiate between the 3rd and 5th day after the transection and then started to proliferate into the defect. Labelled perineurial cells were completely absent, when the minifascicles were fully developed in the neuroma. The epineurial fibroblasts started to proliferate during the 1st day. Even 6 weeks after transection the multiplication rate was about ten fold that of the controls. The results are discussed with special reference to clinical nerve repair.