Histomorphological Assessment of Spermatogenesis in African Catfish Clarias gariepinus with reference to Spermatogonial Proliferation

The fresh water catfish is the most predominant species of the teleost bred in captivity in Nigeria and has provided a model for the study of reproduction in aquatic vertebrates, but information on the number of mitotic divisions and spermatogonial generations remains inconclusive. This investigation aimed at assessing the number of generations of spermatogonia produced prior to meiotic division during spermatogenesis. Results indicate that spermatogenesis occurred in cysts and germ cells at the same stage of maturation formed clones round the Sertoli cell. Spermatogonia went through 5 rounds of mitotic divisions to produce 6 generations of B clones (B1-B6) before producing primary spermatocytes, secondary spermatocytes and haploid spermatids . The process of spermiation was not synchronized in all clones of the cysts. Cellular maturation and spermiation occurred in the most advanced clones. Each cyst appeared to simulate the spermatogenic process that occurs in the seminiferous epithelium of mammalian testis. It is concluded that spermatogenesis in captive bred African catfish Clarias gariepinus is cystic, and that spermatogonia arrangement in the cysts is unrestricted and progresses through 5 mitotic divisions to produce 64 spermatogonia type B , 100 mono-flagellated spermatozoa. Approximately, 68% germ cells complete spermatogenesis, following 32 % germ cell loss.