Absence of a complete block to polyspermy after fertilization of Mytilus galloprovincialis (mollusca, pelecypoda) oocytes.
Mytilus galloprovincialis oocytes undergo monospermic fertilizations (1 sperm nucleus/oocyte) over a wide range of sperm-oocyte ratios beyond which the number of penetrating sperm increases either linearly or exponentially over 10 min. Artificial activation of oocytes by KCl or the ionophore A 23187, up to the polar body extrusion stage, allows successful fertilizations upon a subsequent insemination. No organized and complete detachment of supernumerary oocyte-bound sperm is detected after fertilization. Reducing the external Na+ concentration promotes a higher rate of fertilizations. These results suggest that no complete block to polyspermy is established in this species but that a partial block, Na+ dependent, might be sufficient to ensure monospermic fertilizations under natural conditions.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D005260:Female; D005306:Fertilization / Q000187:drug effects; D008297:Male; D008974:Mollusca / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010063:Ovum / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013084:Sperm-Ovum Interactions / Q000187:drug effects
D000001:Calcimycin; D011189:Potassium Chloride; D012964:Sodium