Penetration of zona-free hamster eggs in vitro by goat spermatozoa preincubated in the reproductive tract isolated from a maturing gilt.

When goat spermatozoa were preincubated for 5-5.5 hr in the isolated uterus and oviduct from a maturing gilt, they developed the ability to penetrate zona-free hamster eggs in vitro. Overall penetration rates were 17% and 0%, respectively, 1 hr after insemination, and these increased to 59% and 54% 2 hr later. The penetration rates were not improved by incubation longer than 2 hr after insemination up to 5 hr. Goat spermatozoa preincubated for 5 hr in a m-KRB solution with or without goat serum penetrated zona-free hamster eggs with difficulty. The results suggest that a functional change in the ability of goat spermatozoa to penetrate zona-free hamster eggs may occur in the reproductive tract of different species.