Glycoproteins of the mammalian oocyte's extracellular integument, the zona pellucida, are female-specific macromolecules important for sperm-egg interaction and, potentially, contraceptive vaccine development. Functioning as ligands for sperm-associated zona-binding proteins, specific zona glycoproteins are known to mediate sperm-zona adhesion and the subsequent zona-induced sperm acrosome reaction, two early events in the fertilization process. According to the current paradigm, carbohydrates are the structural elements of zona macromolecules responsible for ligand activity. The zonae of diverse species share a common architecture being comprised of three glycoproteins, termed pZPA, pZPB and pZPC. Using the pig as a model, we have determined that pZPB-pZPC heterocomplexes are high affinity ligands for sperm-associated zona receptors. This project seeks to characterize the structures of pZPB and pZPC N- and O-linked sugar chains and elucidate their role in ligand-receptor interactions. The structures of N-linked oligosaccharides released from intact pZPB and pZPC glycoproteins and site-specific glycopeptides are currently being investigated using MALDI-MS in combination with sequential exoglycosidase digestions. These data will provide fresh insights concerning structure-function relationships of zona carbohydrates.