Zinc effects on mouse spermatozoa and in-vitro fertilization

The fertilizing ability of mouse epididymal and capacitated spermatozoa was tested by mixing with normal or zona-free ova. In the presence of Zn2+, the epididymal spermatozoa failed not only to penetrate the zona pellucida but also to fuse with zone-free ova, while no effect was observed on capacitated spermatozoa. Zn2+ also inhibited fertilization with spermatozoa preincubated in Ca2+-free medium. However, shortly after the addition of Ca2+ to the preincubated spermatozoa, Zn2+ lost its fertilization inhibitory activity.