Experimental evidence for the humoral stimulation of ripening of the gametes and spawning in the polychaete Arenicola marina (L)

Abstract

The spawning of the lugworm immediately follows the ripening of the gametes. The gonoducts (nephromixia) automatically accept free spermatozoa and fertilizable eggs, i.e., eggs in metaphase of the first maturation division, so that shedding occurs. Spawning was inhibited by decerebration. Examination of the gametes in decerebrated worms at intervals after the normal breeding season indicated that they had failed to ripen. The spermatozoa were bound together in morulae and the eggs remained in suspended prophase of the first maturation division. Controls spawned normally in the laboratory. Implantation of prostomiums in the body cavities of decerebrated worms failed to restore the capability of spawning. However, both decerebrated males and females were induced to spawn by administration of prostomial homogenates although females only responded to homogenate prepared from female prostomiums. It is suggested, tentatively, that the hormone promoting the maturation of the eggs and spawning of females may be specific to the female brain. An initial analysis of the substance in the prostomium stimulating the spawning of male worms is described.