Morphological study of the Lingual papillae of Jentink's flying squirrel (Hylopetes platyurus)

This study describes the anatomy and histology of the tongue in the Jentink’s flying squirrel (Hylopetes platyurus), a rodent native to Indonesia (Borneo and Sumatra). We examined the characteristics of the tongue using scanning electron microscopy (SEM) and light microscopy (LM). Macroscopic observations revealed three distinct regions: the apex, corpus (body) and radix (root). The dorsal surface of the apex was characterized by a median groove and lacked the lingual prominence that is common in many rodents. SEM and LM revealed the distribution of papillae over the dorsal surface of the tongue. The papillae could be categorized as mechanical papillae (filiform, conical, large conical) and gustatory papillae (fungiform, foliate, and vallate). Filiform papillae covered the apex and the anterior two-thirds of the corpus. Fungiform papillae were distributed among the filiform papillae from the apex to the corpus, whereas the foliate papillae were present only on the apex. Conical papillae were located on the posterior of the corpus, and the large conical papillae were on the lateral surface of the lingual radix. Three vallate papillae were arranged in a "V" pointing toward the larynx on the posterior part of the radix. This research provides the first detailed observations of the lingual papillae in Hylopetes platyurus. The shape, structure and distribution of papillae are described and compared with those in other rodent species.