Physiology of Finfish and Shellfish (2+1)

3.1.6. Testis and spermatogenesis

Spermatozoa or sperm are formed from the germ cells via a series of developmental changes known collectively as spermatogenesis or the process by which sperm cells are formed in the testis is called spermatogenesis or spermiogenesis.

Spermatogenesis involves an initial proliferation of spermatogonia through repeated mitotic divisions and growth to form primary spermatocytes. Primary spermatocytes then undergo reduction division (meiosis) to form secondary spermatocytes. Division of the secondary spermatocytes results in the production of spermatids, which then undergo metamorphosis to the motile spermatozoa. (Fig).