[Quantitative studies on the regeneration of myelinated nerve fibers. III. Variations in the number and size of regenerated fibers after localized freezing].

The number and size of myelinated nerve fibers have been determined at standard levels in the nerve to medial head of right and left gastroenemius muscles of 45 rats in which the left sciatic nerve had suffered an localized freezing. The nerves have been observed from 10 to 720 days after the operation. In the contralateral nerve, the number of myelinated fibers decreased in average to 18.8%, the mean diameter to 11,2%. Male rats appeared to be more sensitive than female to the effects of the operation. In the regenerating nerve, the number of myelinated fibers returned to normal during 4th week and later increased up to a mean of 124%. Their distribution became bimodal after the 60th day. Both histograms could be superposed by the 330th day and the mean diameter came back to normal soon afterwards.