Spontaneous Coronary Arteriosclerosis in Repeatedly Bred Male and Female Rats.

• The spontaneous development of generalized arteriosclerosis in several strains of repeatedly bred male and female rats has been reported. The arterial lesions remain microscopic in the male but in the female breeder the lesions become more prominent and can be easily recognized grossly. Of particular importance is the fact that these arterial lesions develop spontaneously although the rats are fed a diet which has a low fat content (4%). Further, the development of the arterial lesions can best be correlated with the number and frequency of breedings. In addition, the arterial changes appear in anatomical sequence. That is, after the lesions have developed throughout the length of the main aorta, the coronary arteries then begin to show evidence of degenerative change. When arteriosclerosis has become advanced in both systemic and coronary artery beds, the cerebral arteries begin to show arterial damage. The changes in the carotid and cerebral arteries have been reported. In this paper, the changes in the coronary arteries and hearts of these breeder rats will be described.