Morphological and histomorphological structure of testes of the catfish "Clarias gariepinus" from Egypt

Knowledge of the normal reproductive biology of catfish is of a great importance not only for better understanding of the theory of fish development, but also to be used as a baseline for understanding the pathological changes results form exposure to harmful toxicants. Thus, the aim of the current study was to elucidate the gross anatomical and light microscopic features of the testes of the catfish "Clarias gariepinus" from Egypt. The present study was carried out on 36 mature male catfish (Clarias gariepinus) collected monthly during the spawning period (April-September) throughout the Nile River, crossing Sohag city in Egypt, in the year 2011. Samples were processed for light and electron microscopy. Each testis consisted of two regions, a fringed outer lateral region and a smooth sagittal-medial region. Histological examination revealed that the testis was covered with a highly vascular connective tissue capsule sending septa dividing the testis into seminiferous lobules separated by interstitial connective tissue containing steroid secreting Leydig cells. Seminiferous lobules were made up of spermatogenic cells and Sertoli cells; the spermatogenic cells located within cysts formed by the cytoplasmic projections of the Sertoli cells. According to the maturation stages, the seminiferous lobules were classified into three types. Spermatogenic seminiferous lobules were lined with different spermatogenic cells but had few or no spermatozoa. Pubertal seminiferous lobules were packed with spermatozoa with few spermatogenic cells. Spent seminiferous lobules contained remnants of spermatozoa and spermatogenic cells. In conclusion, the testis of catfish Clarias gariepinus from Egypt was similar in structure to other catfish and teleost species.