Macroscopic and Microscopic Study of Tongue Papillae in Rahmani Sheep (Ovis aries): Morphometric Analysis, Light and Scanning Electron Microscopic Study

Abstract

The tongue and papillae are vital structures for evaluating texture, taste and quality of food, yet little is known about these structures in Rahmani sheep ( Ovis aries ). Nine mature male tongues underwent gross inspection and morphometric analysis. Scanning electron microscopy (SEM) and light microscopy following hematoxylin and eosin, Periodic Acid-Schiff, Picrosirius red with alcian blue, and methylene blue staining were used to describe morphology. The tongue possessed gustatory (fungiform and circumvallate) and mechanical (filiform, conical, and lenticular) lingual papillae. Filiform papillae consisted of the main and numerous subsidiary and tertiary papillae. Five varieties of conical papillae were present on the tongue's dorsal surface. On the torus linguae, two lenticular papillae types were discovered. Most fungiform papillae were button shaped with prominent taste bud pores. Both sides of the torus linguae had rows of circular, elliptical, pyramidal, and oval circumvallate papillae. Flat, broad, undulating annular rods and papillary grooves surrounded the papillae. The lingual surface had several lingual gland holes, which expanded at the root and varying lingual papillae were observed. Light microscopy confirmed these findings and revealed the fundamental trilaminar architecture of the dorsal lingual mucosa, with particular attention to collagen. Specialized circumvallate papillae were demonstrated alongside deep Von Ebner's serous glands and their ducts. The hierarchical organization of associated primary and secondary filiform papillae was also shown. This detailed novel report is the first to show flattened conical papillae on the glossopalatine arch and the root of the tongue. It is the first to show differently shaped lingual gland apertures on the dorsal surface of sheep tongues.