The comparative histology of the testis of two cultured clariid species (Clarias gariepinus and Heterobranchus bidorsalis)

Abstract

Sexually active (brood stock) males of Clarias gariepinus and Heterobranchus bidorsalis were histologically examined in this experiment. The objective is to examine histologically the testes of these two species and to compare their testicular structures with one another. The specimens were dissected and their testes removed whole and preserved in Bouin‟s fluid for 72hours. Tissue samples were collected and dehydrated through graded concentrations of alcohol. The tissues were cleared in two jars of xylene for one hour and then embedded after passing through the four changes of paraffin wax at 60^oC. Paraffin sections of 5micron thick were mounted on clear albuminized slides, dried in an oven and stained with Haematoxylin and Eosin (H & E) and Periodic Acid Schiff (PAS) and subsequently viewed under light microscope. Our findings showed that the seminiferous tubules of the Clarias gariepinus testis had wider lumen than those found in Heterobranchus bidorsalis. On the other hand the interlobular spaces were extensive in the Heterobranchus bidorsalis than that of Clarias gariepinus. The findings can serve as foundation to further research on the structural and ultrastructural variations in the testes of these species thereby enhancing the breeding and the hybridization of both species for genetic improvement.

Key Words: Sexually gravid, Histology, Clarias gariepinus, Heterobranchus bidorsalis