Peculiarities in the organization of testis of Ophidian sp. (Pisces Teleostei). Evidence for two types of spermatogenesis in teleost fish

The walls of lobules in the testis of Ophidion sp. are composed of Scrtoli cells and young germinal cells (spermatogonia and spermatocytes). Spermatocytes are linked by cytoplasmic bridges. The associations of Sertoli cells and spermatocytes constitute true cysts. Meiosis takes place in the cysts. When meiosis is complete, cysts open. Spermatids are released into the lumen of the lobules and the cyloplasmic bridges break down. Spermiogenesis occurs in the lumen. Spermatids at various levels of spermiogenesis are then mixed with ripe spermatozoa. In teleosts we thus recognize two types of spermatogenesis: a cystic type where spermatogenesis is completed within cysts, and leads to synchronous development of germ-cells; and a semi-cystic type, where spermatogenesis occurs partly outside cysts. This may produce asynchronous spermatogenesis.