Abstract
Changes in the nervous system and musculature of normal 34-month-old rats are described. Wallerian degeneration as well as segmental demyelination were observed in the peripheral nervous system, with changes more severe in the sciatic than in the brachial nerves. Signs of nerve-fibre degeneration were also seen in the cord and lower brain stem. The degenerative changes were usually mild, but in a number of animals there was severe degeneration of the gracile tract and lateral columns. Other changes in the nervous system included lipochrome pigment in nerve cells and other cellular elements throughout brain and cord, and eosinophilic bodies in the lower brain stem and cord. In some animals the ventricular system in the brain was dilated. Changes in the skeletal musculature were believed to represent neurogenic muscular atrophy secondary to changes in the nervous system.