Three-dimensional study of the lingual papillae and their connective tissue cores in the Nile fox (Vulpes vulpes aegyptica) (Linnaeus, 1758).

The Nile fox (Vulpes vulpes aegyptica) is the largest Egyptian fox being distributed in different geographical regions in Egypt. The current study aims to investigate the three-dimensional features of the lingual papillae and their connective tissue cores (CTCs) in the Nile fox by using scanning electron microscopy. Five types of lingual papillae were present on the dorsal aspect of the tongue: filiform, conical, fungiform, vallate, and foliate. Generally, the filiform papilla consisted of a main papilla and several accessory processes emerged from its basal part. Filiform papillae differed in their length, shape, and number of accessory processes according to the region of the tongue. Two types of filiform CTCs were present; either conical-shaped or consisted of a main core and several accessory cores. Two types of conical papillae and two types of conical CTCs were demonstrated; elongated triangular-shaped and large conical-shaped. In addition, two types of fungiform papillae were demonstrated; rounded-shaped and elongated fungiform papillae. The fungiform CTCs were thick columnar in shape with several parallel vertical folds. Six vallate papillae were present, they were surrounded by a groove and either conical papillae or an annular pad. The surface of the vallate CTCs and their surrounding pad had small protrusions. The foliate papillae were represented by 5-6 laminae separated by grooves. The foliate CTCs appeared as oval grooves limited by laminar projections. Regional variations of the filiform papillae and the presence of three types of gustatory papillae suggest specialization of the Nile foxes' tongue to their omnivorous diet.