BINDING OF SPERMATOZOA TO THE PERIVITELLINE LAYER IN THE PRESENCE OF A PROTEASE INHIBITOR

The extracellular investment of oocytes in a number of species contain s species-specific receptors to which spermatozoa bind as a prelude to fertilization; however, Little is known about the nature and distribu tion of sperm receptors in avian oocytes. In order to elucidate the ea rly step of fertilization in birds, we observed the binding of spermat ozoa to the perivitelline layer (PL) of quail ova. When the PL obtaine d from the largest follicles were incubated in vitro with spermatozoa, perforations were observed. The presence of trypsin inhibitors during incubation inhibited the sperm-induced perforations of the PL and bin ding of spermatozoa to the PL could be observed. The number of spermat ozoa bound to the PL increased in the ovum from more mature follicles, and concentrated binding of spermatozoa to the PL overlying the germi nal disc region was observed in the largest follicle. The number of sp ermatozoa bound to the PL overlying the germinal disc region decreased in the oviposited eggs. These results demonstrate that sperm receptor s exist in the PL over the germinal disc in the mature follicle.