Practice question

Among cortical granule components massively released during slow block to polyspermy are large sulfated mucopolysaccharides, hyaline and glycoproteins that hydrate explosively upon discharge into extracellular space. Their high colloid osmotic pressure and water-binding capacity draws surrounding seawater and ovular fluid into perivitelline space between egg plasma membrane and elevated vitelline envelope, causing dramatic space expansion and envelope elevation that physically separates sperm receptors from oolemma. Subsequent hardening by peroxidase-mediated dityrosine crosslinking and transglutaminase isopeptide crosslinking then freezes envelope in raised position. Glycosaminoglycan-driven swelling crucially creates space for lifting envelope, while proteases digest receptors and ovoperoxidase hardens structure independently.