Gut morphology and morphometry in the epauletted Wahlberg's fruit bat (Epomophorus wahlbergi, Sundevall, 1846)

The morphological adaptations of the fruit bat small intestine to which the high functional efficiency could be related and the possible landmarks del ineating the various parts of the gut were examined. The stomach was the ca rnivorous type with large rugae spanning the entire luminal aspect down to the pyloric sphincter, which was reflected internally as a prominent fold. Externally, the intestine was a continuous tube uninterrupted by any struct ures. The cranial fifth of the small gut had long, branching and anastomosi ng villi, which caudally turned to finger-like discrete structures that bec ame rather short and stumpy and diminished at the beginning of the colon. T he colon had longitudinal folds that were macroscopical ly discernible from the mucosal aspect of the opened intestine and that continued into the rec tum. The small gut formed 94% of the whole intestinal length, the colon and the rectum taking 4 and 2%, respectively. Ultrastructurally, the enterocyt e showed a prominent brush border and the lateral membranes were modified i nto numerous tortuous interdigitating processes. Adjacent enterocytes were joined by these processes through desmosomes. The processes also participat ed in pinocytotic fluid uptake from the intercellular spaces with resultant numerous intracellular vacuoles of varied sizes. Solutes absorbed into the cells were probably first passed into the intercellular compartment to cre ate a concentration gradient thus enhancing further absorption into the cel l. We conclude that the uniquely elaborate ultrastructure of the enteric ep ithelium coupled with the vast microvillous surface areas reported elsewher e are partly responsible for the very high absorption rates reported in the fruit bat small intestine.