Anatomical description of the central nervous system and the vertebral column of the African catfish (Clarias gariepinus)

Abstract

Wildlife anaesthesiology is a dynamic and emerging field. Different species of aquatic and wildlife species are gradually gaining more recognition for their use in research, as pets or as food. This study highlights some gross and histological features of the central nervous system and vertebral column of the African catfish (Clarias gariepinus). Twenty male adult African catfish (Clarias gariepinus) were used for this experiment. Brains and spinal cords were harvested and linear measurements obtained. Routine stains Heamatoxylin and Eosin and Cresyl Violet stain were used for histological preparation. Grossly, the brain was lobulated, appearing like follicles. Relative brain weight was 0.11± 0.02%. Average fork length was 439.40 ± 21.26 mm, and the calculated encephalisation quotient was 0.084 ± 0.013, making the catfish appear to be at a lower level on the intelligence ladder. Histology revealed a telencephalon with indistinct layers, unlike that observed in mammals. The cerebellum was also unique, with the Purkinje cells appearing like spindle-shaped neurons and irregularly distributed in the molecular layer. The stroma of the molecular layer of the cerebellum was seen to form tracts which extend into the granular layer. The number of vertebral bones were consistent in all animals but there was a variation in the number of spinal nerves observed. The distinguishing features of the vertebral bones were highlighted and the presence of a ventral foramen, partly enclosed by the transverse processes was discussed. Results obtained from this study will find application in comparative anatomy, fish anesthesiology and possibly surgical maneuvers involving neurological diseases.