Injection of a soluble sperm fraction into sea-urchin eggs triggers the cortical reaction.
Fertilization membranes form around unfertilized sea-urchin eggs after microinjection of a soluble spermatozoa fraction isosmotic with seawater. This demonstrates that the spermatozoon contains a chemical that triggers an increase in cytosolic calcium, leading to exocytosis of cortical granules. It also demonstrates that the triggering mechanism does not require an externally-activated egg-membrane process. Further experiments show that the chemical trigger is not calcium.
D000818:Animals; D002118:Calcium / Q000502:physiology; D005089:Exocytosis; D005260:Female; D005306:Fertilization; D008297:Male; D008845:Microinjections; D010063:Ovum / Q000502:physiology; D012617:Sea Urchins / Q000196:embryology*; D013045:Species Specificity; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology
D002118:Calcium