Spheroids (axonal dystrophy) in the central nervous system of the dog. I. Light microscopic observations.

Abstract

The spheroids in the brain and spinal cord were examined lightmicroscopically in 55 dogs (1 month to 18 years of age). Their shape varied from round to oval and was sometimes ellipsoidal or irregularly elongated, and the size ranged from 5 to 200μm in diameter. The spheroids were acidophilic and argyrophilic, histochemically positive for protein reaction but negative for nucleic acid reaction. As a new finding, PAS positive concentric round bodies were found within the spheroids in aged dogs. In the brain, the most constantly affected area was the dorsal column nuclei, especially in the gracile nucleus in the medulla oblongata. In the spinal cord, caudal segments from the lumbar to the cauda equina were noticed as the predilection sites, and the spheroids were more frequently found in the substantia intermedia hnd ventral column. The occurrence of the spheroids tended to increase with age and was marked in chronic wasting disease such as tumor cachexia and severe filariasis.