Male rats were raised to different ages in cohabitation, i.e. with sexually receptive females, and unmated males were raised with spayed females or in all-male groups. The size of the testes, several accessory reproductive organs, kidneys and adrenals was compared. The body composition of the males was determined at 286 days of age.
At all times after puberty, the males raised with receptive females had larger accessory reproductive organs and kidneys. At 286 days of age some of the accessory reproductive organs of the unmated males were 35 to 40% smaller, a degeneration of the testes and the coagulating glands had begun and their bodies contained 72% more fat and 6% less total ash. The findings suggest that in the male rat cohabitation is necessary for the proper maintenance of testicular androgen secretion.