Practice question

Acrosome is large cap-shaped vesicle covering anterior half of sperm nucleus, derived from Golgi apparatus and considered modified lysosome packed with hydrolytic enzymes. Upon capacitation and zona binding, calcium-dependent exocytosis releases outer acrosomal membrane fusing with plasma membrane, liberating hyaluronidase, acrosin serine protease and glycosidases. Hyaluronidase disperses cumulus hyaluronan matrix, acrosin digests zona glycoproteins locally. Exposed inner acrosomal membrane displays secondary receptors for ZP2, ensuring sustained binding. Specialized secretory organelle thus enables enzymatic penetration of egg investments essential for reaching oolemma for fusion and activation.