The mucosa of the rabbit vagina: a proposed experimental model for correlated morphofunctional studies in humans.

In order to suggest a valid experimental model for correlated studies regarding the complex phenomena of reproductive biology in humans, light (LM), transmission (TEM) and scanning electron microscopic (SEM) observations were carried out on vaginae of sexually mature New-Zealand albino rabbits, both in estrus and at 5 h after mating. To avoid artifacts depending upon the operative times for specimen removal and, in particular, to well visualize the inner surface of this organ, vaginal irrigation with fixative was performed prior to the surgical removal. Our data demonstrate that the upper 2/3 of the vaginal duct form a kind of 'cervico-vaginal canal' which shares many histological features with the human endocervix. In fact, this portion is lined within by a monostratified epithelium provided with tall microvillous and ciliated cells and often invaginated in crypts. After mating, the microvillous cells showed evidence of secretory activity, exhibiting dome-like luminal surfaces. Secretory droplets often contacted cilia and spermatozoa present in the mucosal furrows and crypts. Because of these singular features and the morphofunctional interactions between vaginal epithelium and male gametes, we believe the rabbit to be a helpful model for comparative biology in humans, concerning sperm capacitation and the general reactivity of the female genital tract during the reproductive cycle.