The Involvement of Sperm and Egg Glycosidases in Animal Fertilization

Abstract

A number of glycosidases have been detected in the seminal fluid of the male genital tract of mammals and in sperm and eggs of many invertebrate and vertebrate animals. Although some of these enzymes have been isolated and characterized, the elucidation of their presumed function in the fertilization process proved to be rather difficult. In relatively recent investigations evidence was presented that glycosidases are involved in binding of sperm to the acellular egg-coats of ascidian and mouse eggs, a step that is indispensable for successful fertilization. Furthermore, hyaluronidase and possibly β-N-acetylglucosaminidase from mammalian sperm are claimed to be involved in the penetration of the acellular egg coats, particularly through the cumulus oophorus. The precise mechanism of sperm penetration and whether it can be applied to fertilization in all mammals is still debated. Ascidians and mice are so far the only animals from which evidence exists that egg-bound glycosidases might be involved in the slow block to polyspermy.In summary, good evidence exists that glycosidases play an essential role in gamete interactions, particularly in the interaction of the sperm cell with the acellular egg matrix.