PROMOTION OF FERTILIZABILITY OF SPISULA OOCYTES WITH 5-HYDROXYTRYPTAMINE

5-hydroxytryptamine (5-HT) at a final concentration of 5 mum triggered dissolution of germinal vesicle (GVBD) in Spisula oocytes suspended i n natural sea water (NSW). The maturation inducing potency of 5-HT dec reased with decreasing concentration and was ineffective at/or below 5 00 nm. Incubation of Spisula oocytes with low concentration of 5-HT (1 0 nm) increased fertilizability of oocytes by fresh motile Spisula spe rm. The present findings suggest that the action of 5-HT is to sensiti ze Spisula oocytes to interact with sperm, to promote maturation and t o facilitate fertilization.