DENERVATED CHANGES IN MUSCLE FIBERS AND MOTOR END-PLATES

A histochemical study was conducted on the anterior tibial muscle of rats after transection of the right sciatic nerve at the proximal third of the thigh. Fibrillation was most prominent at the 4th week after denervation and even at the 7th month tiny fibrillations were infrequently recognized. The denervated muscle reduced its wet weight rapidly for the first one nonth and thereafter the decrease was gradual. From the 3rd month onwards muscle weight loss reached the plateau where the denervated muscle weighed about 15 to 20% against the control. The decrease of S. D. H. activity in the red muscle fibers resulted in histochemical undifferentiation of muscle fiber types, particularly from the 2nd month onwards after denervation. Motor end-plates stained by Wachstein, Meisel and Falcon's method became less visible in the course of time up to the 2nd month after denervation, but thereafter their staining intensity increased gradually with the abnormal internal structure of the synaptic folds.