Stomach as an additional respiratory organ, as exemplified by Ancistrus multispinnis (Couvier et Valenciennes, 1937), Siluriformes, Teleostei

The micro- and ultrastructure of intestinal wall of 29 individuals of Ancistrus multispinnis was examined under the scanning and transmission electron microscopes. The presence of cellular structures, analogous to type I pneumocytes forming the mammalian pulmonary lining, was identified in the stomach corpus. Cells of a morphology similar to that of neuroendocrine cells of the salamander lungs were found as well. The pulmonary-cerebral capillaries were identified in the stomach corpus. The observations demonstrated that the stomach of A. multispinnis was able to function as an additional respiratory organ