The neurohormonal induction of the release of oocytes and sperm from Pecten maximus

In order to induce in vitro maturation of Pecten maximus oocytes, experiments were carried out using different concentrations of the serotonin and dopamine agonists TFMPP, 8-OHDPAT, quinpirole and bromocriptine. The greatest germinal vesicle breakdown (GVBD) occurred using TFMPP. Metaphasic blocks were rarely observed. Oocytes treated with TFMPP at 10 super(-3) and 5x10 super(-4) M could be fertilized at low levels. The maximum fertilization rate recorded was 23%. A second series of experiments was conducted to determine the effects of serotonin, dopamine, the agonists cited above and PGE sub(2) on the release of oocytes and sperm from P. maximus. These inducers were injected into both the male and female parts of the gonads and spermiation was systematically tested approximately 20 minutes following injection. No oocyte release was recorded, except after one injection of 8-OHDPAT at 5x10 super(-4) M; the effect of 8-OHDPAT on the release of oocytes was nevertheless insignificant.