Anatomical features and histology of the digestive tract of two African detritivorous Cyprinids, Labeo senegalensis (Valenciennes, 1842) and L. coubie (Ruppell, 1832)

Abstract

The anatomy and morphology of the digestive tract of Labeo senegalensis and L. coubie were described from studies using light microscopy. The sub terminal fleshy mouths are covered with papillae and fringes in both species. The vomero-palatine organ of L. senegalensis is more developed than in L. coubie. They both have an average of 64 ±2 very fine pair of gill rakers of mean length of 4mm. Individual raker in each pair is positioned at right angle to each other. The intestinal coefficients of the two species are 16.52 ± 0.66 (r = 0.96; p< 0.0001) for L. senegalensis and 18.01 ± 0.57 (r = 0.97; p< 0.0001) for L. coubie. The gut is uniform from the mouth to the anus except for a slight esophageal swelling and increases with the size (age) of the fish. The gut consists of four layers: serosa, muscularis, submucosa and mucosa. The histology of the gut of the two species reveals a foregut with slender finger-like folding of the submucosa and the mucosa. The midgut has mucosa that is very much enlarged with reticulated concavities and foldings while the hindgut has blunt thick folding of the submucosa and mucosa.

Keywords: Labeo, feeding, digestive tract, anatomy, detritivore, histology