Comparative morphology of the lingual papillae and their connective tissue cores in the tongue of the American mink, Neovison vison.

We observed the morphology of the lingual papillae (filiform, conical, fungiform, and vallate papillae, and lateral organ) and their connective tissue cores (CTCs) in the American mink (Neovison vison) using light and scanning electron microscopy. Filiform papillae were distributed on the apex linguae and rostral regions of the corpus linguae. Conical papillae were distributed over the caudal region and absent in the radix linguae. Numerous ridges were present in the radix linguae. Four to six vallate papillae were situated at the border between the corpus and radix linguae. Instead of foliate papillae, a pair of lateral organs was situated on the caudal edge of the corpus. The epithelial surface of each filiform papilla consisted of a single main process and 10-12 accessory processes. Notably, filiform papillae in the apex linguae exhibited morphological variation, and some were dome-like and lacked processes. In contrast, filiform papillae on the rostral part were not variable, were extended to a sharp tip, were associated with an eosinophilic stratum corneum, and lacked nuclei. The CTCs of the filiform papillae consisted of a main core and slender accessory cores surrounding a concavity. Those in the apex linguae were similar in appearance and consisted of main and adjacent accessory cores. The fungiform papillae had a dome-like epithelial surface and their CTCs were columnar, with upper concavities and flanges. The simplified lingual morphology of the American mink, particularly in the filiform papillae in the apex linguae, may be influenced by its diet and semiaquatic lifestyle.