CORRELATION OF ADRENOCORTICAL HISTOPATHOLOGY WITH ARTERIOSCLEROSIS IN BREEDER RATS

Abstract

Spontaneous arteriosclerosis develops in repeatedly bred male and female rats. Virgin rats of an age comparable to breeder rats do not develop arteriosclerosis. The arteriosclerosis becomes increasingly severe with each successive breeding. In a parallel manner, the thymus gland involutes and the adrenal glands become hypertrophied and hyperplastic with each breeding. During the early stages of the development of arteriosclerosis, the adrenal cortex shows storage of lipids. With continued breeding, the zona glomerulosa increases in width and becomes depleted of lipid. In some cases, growth of the adrenal medulla causes compression of the cortex against the capsule of the gland and the pleomorphic nature of the medullary cells resembles a phaeochro-mocytoma. In some female breeders with severe arteriosclerosis the adrenal cortex shows severe haemorrhage and thromboses causing marked reduction of the cortex. The histophysiological changes observed in the adrenal cortex of breeder rats are believed to be analogous to conditions seen in humans with hyperadrenocorticism or Cushing''s disease. It is suggested that there may be a close correlation between the abnormal adrenal function engendered by repeated breeding and the development of the arteriosclerosis.