Comparative histological studies on the tongue of three species of Egyptian bats

Abstract

The present study aims to describe the histological structure of the tongues of three species of bats which having different diets and live in different habitates in Egypt. This work was done on three species of bats; the frugivorous bat Rousettus aegyptiacus, the insectivorous bat Rhinopoma hardwickie and the tomb-inhabiting bat Taphozous perforatus. These animals were caught from their natural habitats in Egypt; dissected and their tongues were fixed in the appropriate fixatives for light microscopical investigations. The histological results revealed that the dorsal surface of the tongue of the three bats is formed of three consecutive layers; mucosa, submucosa and muscularis. The mucosal layer is similar in the three bats. It consists of stratified squamous epithelium and contains three types of papillae but this layer is very thick in both insectivorous and tombinhabiting bats. The submucosa also appears thicker in the frugivorous bat than that in both the insectivorous and tomb-inhabiting bats. It is built up of loose connective tissue, small blood vessels and lymphatics. The muscularis is formed of an outer thin layer of circular muscle fibers and an inner thick layer of longitudinal muscle fibers in both the frugivorous and tomb-inhabiting bats but this layer is constructed of circular muscle fibers arranged in different directions in the insectivorous bat. The histochemical results showed differences in the stainability and distribution of neutral and acid mucopolysaccharides in the lingual glands of the three species of Egyptian bats.