Functional morphology of the gut of the tropical house gecko Hemidactylus mabouia (Squamata: Gekkonidae)

Abstract

The purpose of this study was to characterize morphophysiological aspects of the gut of the gecko Hemidactylus mabouia, a predator species of tiny arthropods. Fourteen adult specimen of the gecko H. mabouia were euthanized and fragments of their small and large intestines were collected and processed according to routine methods for anatomical, topological, histological and histochemical analyses. Histological sections were stained with toluidine blue or submitted to techniques for identification of argyrophil and argentaffin endocrine cells, glycoconjugates and alkaline phosphatase activity. The small intestine of H. mabouia is much more extensive and convolute than the large intestine. There are subtle regional differences along the small intestine, as the tubule diameter and height of the inner folds noticeably decrease from the proximal toward the distal segment. There is no caecum between the small and large intestines and the abrupt change in the caliber marks the transition of the small intestine into the large intestine. The large intestine consists of a very dilated proximal segment followed by a short distal segment. The villi are absent, but the tall folds in the internal covering of the small intestine constitute important amplifier structures of the digestive and absorptive area. No mucosal or submucosal glands were observed along the intestine. The epithelial lining of the entire intestine is simple columnar with enterocytes, mucus-secreting cells and endocrine cells. The enterocytes are abundant in the small intestine and the mucus-secreting cells are abundant in the large intestine, which reflects the functional role of these organs. In sum, H. mabouia has small intestine that is longer than the large intestine, which is consistent with the species being a carnivorous reptile.