DENERVATION CHANGES IN MAMMALIAN STRIATED MUSCLE

Abstract

36 adult Australian opossums, Trichosurus vulpecula. were operated to determine how long denervated mammalian striated muscle retained its essential features. The mm. flexor carpi ulnaris and radialis and the pronator teres were completely denervated by section of the median and ulnar nerves. From 9-485 days later the muscles were excised, weighed and examined. Although gross form and appearance were retained, practically all had atrophied 50% or more in 60 days, and individual fiber size had been similarly reduced. Fibrillation and shortening on removal indicated survival of contractile function. The denervated muscle retained its histological features, but these were less well defined after 1 yr. Sub-sarcolemmal nuclei enlarged at first but returned to normal, there being no signs of degeneration or proliferation. End plates always survived and neuro-muscular spindles were unchanged. The perimysium and endomysium became thickened but did not alter the internal structure of the muscle. The vascular picture was unchanged.