Anatomical, Light and Scanning Electron Microscopic Studies on the Air Breathing Dendretic Organ of the Sharp Tooth Catfish (Clarias gariepinus)

Abd-Elmaksoud, Ahmed; Kassab, Mohamed; Sayed, Ahmed Ahmed; Fayed, Masoud

doi:10.21608/jva.2008.45452

Anatomical, Light and Scanning Electron Microscopic Studies on the Air Breathing Dendretic Organ of the Sharp Tooth Catfish (Clarias gariepinus)

Document Type : Original Article

Authors

¹ Department of Cytology and Histology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt

² Department of Histology, faculty of veterinary medicine, Kafr El Sheikh University, Kafr El Sheikh, Egypt

³ Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Damanhur branch, Bostan, Egypt

⁴ Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Kafr El Sheikh University, Kafr El Sheikh, Egypt

10.21608/jva.2008.45452

Abstract

Previously, it has been shown that different species of fishes are adapted in varying degrees for gaseous exchange in both water and air. Our study was carried out on sharp tooth catfish (Clarias gariepinus) obtained from the Nile River, Egypt and fo- cused on the dendretic organ (DO) investigating its anatomical, scanning and light microscopical features. Anatomically, the air-breathing dendretic organ of the catfish was located in the suprabranchial chamber caudodorsal to the gills and composed of two main parts; small and large ones origi- nated by main stems from the second and fourth gill arches respectively. Histologically, the DO either in its main stems or in the smaller branches and in the end bulbs consists of core of elastic cartilage, vascular layer of connective tissue and covering epithelium containing intraepithelial mucous glands. The blood capillaries (channels) were found to originate from the vascular layer and penetrate the covering epithelium. Toward the surface, these capillaries dilate and bulge out due to engorgement with RBCs forming what is called respiratory papillae. The SEM showed that the stem divisions and their bulbus ends contained double parallel rows of paired projections (respiratory lamellae) separated by areas of smooth surface. Moreover, the surfaces were stud- ded with microvilli. In conclusion, the structure of this organ manifests profuse internal subdivision that may produce a particularly large respiratory surface area to extract the oxygen from air. Therefore, the catfish might be one of the most suitable fish for the intensive production in the fish aquaculture.

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