title: Protease activity establishes the block against polyspermy in sea urchin eggs.
mesh_terms: D005260:Female; D005306:Fertilization; D008297:Male; D011480:Protease Inhibitors; D012617:Sea Urchins; D013094:Spermatozoa / Q000187:drug effects*; D014361:Trypsin Inhibitors / Q000494:pharmacology*; D014817:Vitelline Membrane / Q000187:drug effects
chemical_list: D011480:Protease Inhibitors; D014361:Trypsin Inhibitors