BIOLOGY AND ULTRASTRUCTURE OF CNIDARIAN (CLYTIA-HEMISPHERICA, LEPTOMEDUSAE) SPERM - DEMONSTRATION OF AN ACROSOMAL-COMPLEX
Résumé
Mature sperm of Clytia hemispherica were studied by electron microscopy in the gonads, at their exit from the gonads, and at fertilization. The presence of an acrosomal complex at their anterior pole, which has long been a subject of controversy in cnidarians, was demonstrated. A chemoattractant and an inductor of the acrosomal reaction, both released at the animal pole of the eggs, were responsible for the accumulation of spermatozoons and the formation of the acrosomal process. A striated rootlet extending from the pericentriolar region to the plasma membrane was described, and its possible relationship to positive chemotaxis discussed. Ultrastructural modifications of the testes induced by light, a factor controlling spermiation, were investigated.