[Degenerative changes of the myelin fibers of sciatic nerves in aged rats].

Ischiadic nerves of 24-month old rats were examined by electron-microscopic technique. It was established that a large part of myelin fibres had degenerative changes, manifested at various degree. Axonal cylinder was atrophied even to complete disappearance. Myelin fibres endured degeneration, ending with sequestration and fragmentation. In part of the involved fibres the myelin sheaths preserved their intactness, but collapsed due to atrophy of the axon.