The interaction of avian spermatozoa with the perivitelline layer in vitro and in vivo.

The differences in the hydrolytic activity of chicken spermatozoa towards the inner perivitelline layer in situ and when isolated from the ovum were investigated. Points of hydrolysis produced by chicken spermatozoa on the inner perivitelline layer of laid and freshly ovulated eggs were viewed as dark holes after staining with fluorescein-conjugated wheat-germ agglutinin. In laid eggs that had been fertilized in vivo, these holes appeared more frequently on the perivitelline layer overlying the blastodisc at the animal pole than on that overlying the vegetal pole. However, in an assay in which fragments of the inner perivitelline layer from freshly ovulated eggs were incubated with spermatozoa in vitro, points of hydrolysis appeared with similar frequency on the perivitelline layer from over the germinal disc at the animal pole or from that over the vegetal pole. No difference could be demonstrated in the electrophoretic profile of peptides extracted from the inner perivitelline layer at the animal or vegetal pole. The factor(s) responsible for either increased attraction of spermatozoa to, or for increased activity at, the perivitelline layer of the animal pole does not appear to be associated with the perivitelline layer itself.