Practice question

After successful sperm fusion, cortical granule exocytosis rapidly releases paracrystalline protein fraction and enzymatic cocktail into perivitelline space between plasma membrane and vitelline layer. Mucopolysaccharide hydration induces osmotic water influx elevating vitelline envelope away from egg surface. Simultaneously proteases sever connections linking bindin receptors to envelope, while transglutaminase and ovoperoxidase catalyze covalent crosslinking of glycoproteins and newly deposited structural proteins hardening envelope into fertilization envelope, tough impermeable protective coat preventing further sperm entry and shielding embryo from mechanical stress. Hyalin, glycosaminoglycans and acrosomal proteins contribute but driving mechanism is vitelline envelope modification and crosslinking.