Histochemical studies on iron absorption in Ophiocephalus punctatus and Heteropneustes fossilis

Iron absorption in both the teleost fishes Ophiocephalus punctatus and Heteropneustes fossilis, initially starts after 2h of feeding the iron diet. However, at this stage, there is no absorption of iron in the posterior intestine of both the fishes. Absorption initially starts along the brush border of enterocytes of the villi. Later, it gets accumulated in the supranuclear region of the epithelial cells and then through these cells, it is transported into the cores of the villi. The absorbed amount ultimately reaches along the bases of the villi. Through the blood capillaries, which are situated in the submucosa, absorbed iron is passed on to the blood stream. Although, the entire intestine of both the fishes is able to absorb iron but the regional variations have been noted. In contrast to the posterior intestine, the anterior and middle intestine of both the fishes show better iron absorption. The pyloric caeca of Ophiocephalus have comparatively less affinity for iron absorption. However, the intestine of Heteropneustes shows more affinity for iron absorption than the intestine of Ophiocephalus.