Practice question

Zona pellucida comprises sulfated glycoproteins ZP1-ZP4 bearing extensive N- and O-linked glycans that regulate mechanical stiffness and ligand function. Glycan moieties present terminal sialic acid and specific oligosaccharide epitopes recognized by sperm plasma membrane receptors such as galactosyltransferase, influencing species-restricted adhesion and triggering acrosome reaction. Altered glycosylation modifies zona solubility, protease resistance and sperm binding avidity without affecting sperm motility or implantation directly. Deglycosylation experiments reduce but may not abolish binding, underscoring glycans as key modulators of primary sperm-zona recognition and polyspermy block after fertilization.