The dorsal surface of the tongue in mammals shows a wide variation in the distribution and type of lingual papillae in relation to the type and manner of food uptake. The present study is designed to compare morphological and histological aspects of the lingual papillae of the tongues of the guinea pig, Cavia porcellus (herbivorous) the hedgehog Hemiechinus auritus aegyptius (insectivorous) and by light and scanning electron microscopy. The results revealed the presence of three kinds of lingual papillae in the two investigated species; i.e. filiform, fungiform, circumvallate papillae. In H. auritus, other two special types of papillae were found; fez-like and setaceous-like papillae. Filliform papillae were divided into two types; the Type I is pointed, sharp, and long. Type II filiform papillae show resemblance in both species, and they have large triangular bodies, a smooth surface, and bifid or trifid ends. In C. porcellus, only the bifid papillae are observed. In the tongue of H. auritus, Keratohyalin granules are observed at the base of the papillae, whereas in C. porcellus, the keratohyalin granules are located peripherally. The fungiform papillae are large in size and contain many taste buds. In C. porcellus they are restricted at the tip; few are dispersed randomly at the whole surface. In H. auritus, these papillae are densely distributed along both lateral edges. Three circumvallate papillae are found in the posterior part of the tongue of both species. The taste buds are present on the dorsal surface of the fungiform papillae and on the lateral wall of the circumvallate papillae. The present study revealed that the tongue of these two mammalian species exhibits significant micro-anatomical and structural variations that revealed the adaptations to their varying feeding patterns.
Key words: Mammals, Tongue, Lingual papillae, SEM, Histology
|
