Comparative light and scanning electron microscopic study of the lingual papillae in three different mammalian animals; Hemiechinus auritus (Erinaceomorpha: Erinaceidae), Cavia porcellus (Rodentia: Caviidae) and Mustela nivalis vulgaris (Carnivora: Mustelidae)

Abstract

The present study was carried out to describe the histological structure of the tongues of three different mammalian animals which having different diets; Hemiechinus auritus (insectivorous), Cavia porcellus (herbivorous) and Mustela nivalis vulgaris (carnivorous). Also, this study aimed to investigate the morphology of the lingual papillae of the tongues of these animals by the scanning electron microscope. Tissue samples taken from the tongues of five adult healthy animals from each specimen were fixed in the appropriate fixatives for light and scanning electron microscopic investigations. Light microscopy observations showed that the dorsal surface of the tongues of the three animals are formed of three consecutive layers; mucosa, submucosa and muscularis. The mucosal layer consists of stratified squamous epithelium with variable degrees of keratinization and contains different types of papillae. SEM observations revealed that there are three types of papillae (filiform, fungiform and foliate) in Cavia porcellusʾs tongue. But, there are four types of papillae (filiform, fungiform,vallate and foliate) in the tongues of Hemiechinus auritus and Mustela nivalis vulgaris. The filiform papillae are leaf-like simple conical or branched in Hemiechinus auritus and Cavia porcellus, but they take hand-like shape with finger-like processes in Mustela nivalis vulgaris. The fungiform papillae are mushroom-like in shape in the three animals. They are aggregated in two clusters in the anterior part of Cavia porcellus ҆s tongue. Two vallate papillae are observed in Mustela nivalis vulgaris ҆s tongue, but there are three vallate papillae in Hemiechinus auritus ҆ s tongue. Pair of foliate papillae is found in the latero-posterior parts in the tongues of Hemiechinus auritus and Mustela nivalis vulgaris. In conclusion, the results of the present study added to the previously recognized studies of the dorsal lingual papillae of different mammalian animals which having different diets.