The aim of this study was to characterise the tongue in wild-type rats using several microscopic techniques. Warsaw Wild Captive Pisula Stryjek (WWCPS) rats belong to a lineage of wild-caught rats. The study was carried out on tongues of 15 male and 15 female WWCPS rats. Histological, histochemical and ultrastructural studies were carried out. There were no significant differences between the male and female WWCPS rat tongues. There was a median groove approximately 1 cm long in the apex of the tongue that faded caudally. The intermolar prominence was clearly marked in the distal part of the lingual body. Lingual mechanical papillae located on the surface of the tongue formed four subtypes based on their shape: small filiform papillae, giant filiform papillae, thin elongated filiform papillae and wide filiform papillae. Gustatory papillae formed the second group of papillae and were divided into bud-shaped fungiform papillae, a single vallate papilla surrounded by an incomplete papillary groove and foliate papillae, which were a well-formed and composed of several pairs of folds divided by longitudinal grooves. In the posterior lingual glands (mucoserous and serous), acidic sulphated mucin-secreting cells gave a strong AB pH 2.5 positive reaction, and a positive reaction with the AB pH 1.0 stain for acidic carboxylated mucin. Double AB/PAS staining showed the presence of the majority of mucous cells with predominant of acidic mucins. Positive PAS staining showed the presence of neutral mucin. HDI staining demonstrated a weak positive reaction within Weber's glands of the WWCPS rat tongue.
Keywords: Domestication; Laboratory rat; Tongue morphology; WWCPS; Wild rat.