Endocrine Control of Gametogenesis and Spawning in Bivalves

The reproductive process represented by gametogenesis and spawning accompanied by oocyte maturation and sperm motility activation in bivalves undergoes under the endocrine and neuroendocrine control as well as animals. The class name of Bivalvia is a synonym of Pelecypoda in taxonomy, which can be easily recognized because of two bisymmetric valves to cover their soft bodies. Bivalve species are commercially important organisms harvested as capture and aquaculture products in the fishery industry. Development of eggs and sperms during gametogenesis process is a common phenomenon among oviparous organisms. Histological examinations are necessary to describe reproductive events concerning gamete development. Bivalve reproductive maturation is categorized into several stages; differentiation, growing or developing, ripening of gametes, spawning, and resting stages. Bivalve testes contain accessory cells, which presumably play important roles in the processes of spermatogenesis. In the ultrastructural study of spermatogenesis in C. gigas, somatic intragonadal cells are observed among the male germ cells.