The present investigation was planned to study the stomach of two species of bats, frugivorous bat (Rousettus aegyptiacus) and insectivorous bat (Taphozous nudiventris). Histologically, the stomach wall of both species exhibits four general regions, mucosa, submucosa, muscularis externa and serosa. The mucosa is thrown up into numerous villi-like folds (rugae) of various shapes and lengths and consists of gastric cells (surface and neck mucous cells, parietal and chief cells). The submucosa consists of connective tissue, blood and lymph vessels. The muscularis externa consists of outer thin longitudinal and inner thick circular muscle layers. The cytological observations confirmed the histological results. There are some differences between the four gastric cell types of the two species of bats are demonstrated. Additionally, by using Masson's trichrome and azan stains, the collagenous fibres are more numerous, dense and compact in tunica submucosa of T. nudiventris while the fibres are thin and irregular in R. aegyptiacus. In the histochemical study, the distribution of polysaccharides is demonstrated by PAS technique. The mucous cells of surface epithelium seem to secrete high mucin in both R. aegyptiacus and T. nudiventris. The gastric gland, mucous neck cells, and muscularis mucosa of R. aegyptiacus display moderate distribution of polysaccharides less than in T. nudiventris. The gastric cells of R. aegyptiacus have dense content of protein as shown by using BPB dye while muscularis externa and muscularis mucosa are demonstrated with moderate protein contents. In contrary, the gastric cells of T. nudiventris have moderate content of proteins while muscularis externa and muscularis mucosa have high proteins. Acid & alkaline phosphatases (AcP & AlP) activity is detected by azo dye precipitation (Gomori method). The gastric cells of mucosa of R. aegyptiacus have strong AcP activity and is more pronounced in muscularis, submucosa and muscularis of the stomach of T. nudiventris. The AlP activity is concentrated in the mucous cells of surface epithelium and isthmus region in both species of bats. The gastric cells of base and neck regions as well as muscularis and submucosa of stomach have no AlP activity in both species.
Key words: Bats, Stomach, Histology, Cytology, Histochemistry, Enzymes
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