Distal Intestinal Caecum of Farmed African Catfish (Clarias gariepinus Burchell, 1822): A Case Report

The microanatomical characteristics of the distal intestinal caecum were investigated. The histology was typical of tubular organs containing tunica mucosa, submucosa, muscularis and adventitia. The lumen was lined by simple mucosal folds. The covering epithelium was of simple columnar cells containing goblet cells and intraepithelial lymphocytes. The lamina propria contained blood vessels, loose connective tissue and leukocytes. The muscularis mucosae of smooth muscle cells were observed. The submucosa contained loose connective tissue, smooth muscle cells, blood vessels and leukocytes. The tunica muscularis contained a myenteric plexus between the inner circular and outer longitudinal layers of smooth muscle cells. The mucin histochemistry revealed that the goblet cells present contained neutral and acid mucin but acid mucin predominated suggesting an organ with more need for protection against bacteria in the blind ended tube. When compared with the histology of the intestinal segments cranial and caudal to the diverticulum, the features of the caecum were very similar to the segment cranial to it necessitating the conclusion that the diverticulum is the distal intestinal caecum. The histology suggests an organ serving as complementary digestive structure to distal intestine in nutrient absorption without increasing the space occupied by the digestive tract. KEYWORDS: DISTAL, INTESTINAL, CAECUM, FARMED, AFRICAN, CATFISH, CASE REPORT