Abstract
Guinea pigs maintained on the diet described in the previous paper 1 for periods ranging from 35 to 133 days, develop extreme degeneration of the skeletal muscles of the trunk and extremities.
The primary alteration is a waxy or hyaline necrosis of the fibers. This is followed by great proliferation of the muscle nuclei, leading to the formation of so-called “Muskelzellenschlauche” within the intact sarcolemma. There is also active regeneration of muscle cells in the later stages. The disappearance of the degenerated fibers is accompanied by a variable amount of interstitial fibrosis and lipomatosis.
The affected muscles are characterized grossly by a striking pallor.
The prevailing color is yellowish grey, with fine stippling. The muscular tone and elasticity are lost, and the muscle bulk is much reduced in comparison with that of control litter mates.
Careful histological study of the principal organs and tissues other than the skeletal muscles shows no significant change. The brain has not been routinely examined, but in sections of the spinal cord, the motor ganglion cells at all levels are normal in appearance. There are also no obvious lesions in the peripheral nerve trunks. The heart muscle, and the smooth muscle of the gastro-intestinal tract, bronchi, blood vessels and uterus are not affected.
Two young rabbits were examined on the 15th and 16th days after having been placed upon the experimental diet. At that time, they were extremely weak, lying flat on their belly, with limbs flaccid and outstretched. The head could not be raised from the table. The muscles were uniformly pale, grey and translucent, not stippled. Microscopically, the lesions were identical with those seen in the guinea pigs. Necrotic fibers were plentiful, but there had already occurred enormous multiplication of muscle nuclei, and active regeneration of new fibers was in progress.
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