Reproductive physiology and penile papillae morphology of rats after sexual experience.

Research which examined acute and chronic changes in the reproductive physiology and morphology of male rats after mating is reported. A group of sexually experienced (SE) and a group of sexually inexperienced (SI) animals were castrated on day 110 of age. Those animals and a group of SE and a group of SI gonadally intact males were left undisturbed for 30 days, and all animals were killed on day 140 of age. Testes, epididymides, penes and levator ani muscles were heavier in SE males, and those males had increased titres of circulating testosterone. Moreover, testicular sperm production was higher in SE than SI males immediately after the weekly copulatory sessions. Scanning electron microscopic examination of the surfaces of the glans penes revealed that sexual experience slowed the decay of penile papillae. More importantly, SE-intact males possessed uniformly large penile papillae, while the large papillae on penes from SI-intact males were interspersed with smaller papillae in various stages of development. The results suggest that mating provokes substantial changes in the endocrine integrity, fecundity and penile morphology of male rats.