© 1974 by The Society for Integrative and Comparative Biology
Gametogenesis in the Genus Hydra
Department of Zoology, University of Zurich Zurich, Switzerland
This paper comments on the induction of gametogenesis, on microscopical and electronmicroscopical aspects of spermatogenesis and oogenesis and on fertilization in the genus Hydra. Spermiogenesis does not present any peculiarities. The ripe sperm contains no detectable acrosoinc. Egg-formation involves phagocytosis of entire oogonia by growing oocytes. Several oocytes merge to a single oocyte, in which one nucleus becomes the germinal vesicle. The egg shell is formed only when the egg is fertilized. Various factors such as the synchronization of gametogenesis, the length of sexual periods, continuous release of sperm and the long life span of sperm are considered to guarantee the fertilization of the eggs.