Light and scanning electron microscopic study on the lingual papillae in the newborn sea otter Enhydra lutris

The tongue of Enhydra lutris (sea otter), died from brain contusion at the first day of its age, was investigated by light and scanning electron microscopy in this study. Three types of papillae (filiform, fungiform and circumvallate papillae) were present on this tongue. In our evaluation, the filiform papillae were divided into four shapes which were conical, club-shaped, large horny and triangular papillae. The different types of filiform papillae were located in different area of this tongue. The fungiform papillae were divided into two shapes, which were hemispherical or club-shaped, and were distributed among the filiform papillae on the dorsal and the margin of the tongue. These papillae had many taste buds in the epithelium of the dorsal aspect of them. The circumvallate papillae were present in a V-shaped row at the posterior part of the lingual body, and many taste buds lay in the epithelium of both the lateral walls facing the trench and dorsal aspect of the papillary body, and then the ducts of the serous glands opened into the floor of the trenches. The lingual mucosa of the interpapillae area at the pharyngeal part of the tongue contained taste buds and the ducts of the mixed glands opened there. Based on our examination, the lingual papillae of this newborn sea otter had many features which were described to be peculiar to young stage of mammals.