Interactions between spermatozoa and the crypts, cilia, and mucus of the cervix in the ewe.

In ruminants, minor cervical folds, commonly called crypts, temporarily store spermatozoa for a short interval of time between insemination and fertilization. However, the mechanism by which spermatozoa are transported to these crypts and subsequently to the uterus is not known. To study this problem, cervical tissue, which was removed from ewes that were naturally inseminated by rams at estrus, was examined with the scanning electron microscope to determine the physical associations that occur between the spermatozoa and the structural features of the cervix. The study indicates that the spermatozoa generally are not oriented parallel to the longitudinal axis of the cervix, exhibit no consistent association with the cervical cilia, and do not lie in any well defined channels formed by the cervical secretions. Alternatively, the majority of spermatozoa occur as isolated aggregations that lie in or near the shallow folds or crypts of the cervix. The vast numbers of spermatozoa in these aggregations and the lack of any common orientation suggest that some form of external stimulus, such as cervical contractions, might be responsible for the initial mass movement and distribution of spermatozoa in the cervix of the ewe.