Light and Scanning Electron Microscopic Study on the Tongue and Lingual Papillae of the Japanese badgers, Meles meles anakuma

Abstract

We observed the three-dimensional structures of the external surface and connective tissue cores (CTCs), after exfoliation of the epithelium of the lingual papillae (filiform, fungiform and foliate papillae) of the Japanese badgers (Meles meles anakuma) using scanning electron microscopy and conventional light microscopy. Macroscopically, the tongue was elongated anterior-posteriorly and the apex rounded. Numerous filiform papillae and fungiform papillae were distributed all over the tongue except at the root. Seven vallate papillae were observed that had circumferential furrows and were arranged in V-shape. Numerous taste buds were observable in the furrows. Instead of foliate papillae, a lateral organ lacking taste buds was present on the lateral edge of the posterior tongue. Behind the vallate papillae, dome-like lingual tonsils that had globular tonsils were densely distributed in U-shaped arrangement. Rather long conical papillae were distributed around the vallate papillae. At the posterior end of the root of the tongue, lingual papillae were very much attenuated and only fold-like structure was seen. CTCs of filiform papillae had a main rod-like slender core and ovally arranged short accessory cores distributed around the main core. CTCs of fungiform papillae exhibited a columnar like appearance. The lingual papillae of Japanese badger's tongue fundamentally had morphological similarity with carnivore species, included the Pinnipedia.