Anatomical and histological structure of the tongue and histochemical characteristics of the lingual salivary glands in the Persian squirrel (Sciurus anomalus)

This study was carried out to describe the anatomical, histological and mucinous histochemical characteristics of the tongue in the Persian squirrel. This species is a rodent distributed all over the Middle East and recently has been considered a companion animal. Anatomical observations showed the median sulcus on the apex and absence of a lingual prominence in the body. Light and scanning electron microscopy showed that the filiform papillae cover the entire dorsal surface of the tongue, and their sizes increased approaching the root. The fungiform papillae, which contained 1–4 taste buds, were scattered on the apex, margin, body and root of the tongue. Three vallate papillae were observed on the root, each one surrounded by a groove and crescent pad with taste buds on its lateral walls. The foliate papillae on both margins of the tongue contained several laminae with taste buds. The core of the tongue was composed of lingual glands, skeletal muscles and connective tissues. These glands were confined to the body and root, which were composed of serous cells located anteriorly and mucosal and seromucosal cells placed posteriorly. The mucin histochemistry using the periodic acid-Schiff (PAS), alcian blue (AB) (pH 1.0 and 2.5), PAS–AB (pH 2.5) and aldehyde fuchsin-AB (pH 2.5) techniques showed that the mucosal content included both carboxylated and sulfated acidic mucins with neutral mucins. The results of this study could contribute to the knowledge of the morphological characteristics of the wild animal tongue and provide data for comparison with other rodents.