Acrosome Reaction of Cock Spermatozoa Incubated with the Perivitelline Layer of the Hen’s Ovum

A small membranous sheet of the perivitelline layer (PL) isolated from freshly ovulated ova was incubated with cock spermatozoa, and morphological changes of PL and percentage of spermatozoa lacking acrosomes were observed during incubation. The sheet of PL gradually became fragmented as incubation proceeded; fragments were dispersed into a suspension 70 min after the beginning of incubation. To analyze the acrosome reaction induced by the PL, washed or diluted spermatozoa were incubated with or without a PL suspension at 39 C or 41 C. In spermatozoa incubated with the PL suspension, the percentage of spermatozoa lacking acrosomal caps was significantly greater than in controls (without PL). Based on these results, it is suggested that the PL promotes the acrosome reaction by which enzymes contained in the acrosome are released to dissolve the PL.