Sperm penetration into cervical mucus in vitro. I. Comparative studies.

Comparative studies have been carried out on the behavior of human and bovine spermatozoa toward homologous cervical mucus in vitro. In both cases the degree of sperm penetration and the pattern of sperm motility were influenced in a characteristic fashion by prior manipulation of the mucus: the most rapid and extensive penetration, and pronounced unidirectional motion, were seen in mucus that had been aligned linearly. By contrast, spermatozoa from rabbits, guinea pigs, rats, and mice were largely prevented from entering either midcycle human or estrous bovine cervical mucus, regardless of its physical arrangement. The observations on sperm motility patterns and the degree of penetration are discussed in relation to a model of the molecular arrangement of cervical mucus, derived in our laboratory from laser light-scattering spectroscopy.