Penetration of the Zona Pellucida of Eggs of Different Species by Spermatozoa of the Japanese Field Vole, Microtus montebelli

Abstract

Penetration of the zona pellucida of heterologous eggs by spermatozoa of Japanese field vole, Microtus montebelli, was examined in vitro. Spermatozoa from the vole epididymis were more active and survived longer in mKRB medium than did mouse spermatozoa. When vole spermatozoa were used for insemination, they passed through the zona pellucida of mouse and hamster eggs at a high rate. Although many spermatozoa invaded the perivitelline space of such eggs, penetration of the vitelline membrane was not confirmed. The present result suggests that vole spermatozoa have a high ability to penetrate zona pellucida of heterologous eggs.