THE MAMMALIAN ZONA-PELLUCIDA - ITS BIOCHEMISTRY, IMMUNOCHEMISTRY, MOLECULAR-BIOLOGY, AND DEVELOPMENTAL EXPRESSION

Many studies of the molecular and biochemical aspects of mammalian fer tilization have focused on the interaction of the spermatozoa with the zona pellucida (ZP). The zona pellucida, a unique extracellular matri x surrounding the mammalian oocyte, is formed during ovarian follicula r development. Following ovulation of the mature ovum, the spermatozoa must bind to and penetrate this matrix before the fertilization proce ss is completed and the male and female genetic information combine. A lthough numerous models for this interaction have been proposed, the c omplete process has yet to be elucidated. The precise mechanisms by wh ich these interactions occur also vary markedly among different mammal ian species, making it more difficult to establish a unified model. To a great extent, the study of the molecules involved in these interact ions have been limited because small numbers of female gametes are ava ilable for these studies. The recent development of techniques to isol ate large numbers of zonae pellucidae as well as advances in immunolog ical and molecular biology techniques have permitted the detailed char acterization of ZP proteins. Although there is a paucity of informatio n on the post-translational modification and extracellular processing of these molecules which result in matrix formation, a number of prope rties have been elucidated allowing better correlation between the str ucture and function of different ZP proteins among species. This revie w reflects these studies in relation to protein nomenclature and the m olecular complexity of ZP antigens.