Lingual papillae (: papilla) are small structures on the upper surface of the tongue that give it its characteristic rough texture. The four types of papillae on the human tongue have different structures and are accordingly classified as circumvallate (or vallate), fungiform, filiform, and foliate. All except the filiform papillae are associated with taste buds.
In living subjects, lingual papillae are more readily seen when the tongue is dry. There are four types of papillae present on the tongue:
Filiform papillae are the most numerous of the lingual papillae. They are fine, small, cone-shaped papillae found on the anterior surface of the tongue. They are responsible for giving the tongue its texture and are responsible for the sensation of touch. Unlike the other kinds of papillae, filiform papillae do not contain taste buds. They cover most of the front two-thirds of the tongue's surface.
They appear as very small, conical or cylindrical surface projections, and are arranged in rows which lie parallel to the sulcus terminalis. At the tip of the tongue, these rows become more transverse.
Histologically, they are made up of irregular connective tissue cores with a keratin–containing epithelium which has fine secondary threads. Heavy keratinization of filiform papillae, occurring for instance in cats, gives the tongue a roughness that is characteristic of these animals.
These papillae have a whitish tint, owing to the thickness and density of their epithelium. This epithelium has undergone a peculiar modification as the cells have become cone–like and elongated into dense, overlapping, brush-like threads. They also contain a number of elastic fibers, which render them firmer and more elastic than the other types of papillae. The larger and longer papillae of this group are sometimes termed papillae conicae.
The fungiform papillae are club shaped projections on the tongue, generally red in color. They are found on the tip of the tongue, scattered amongst the filiform papillae but are mostly present on the tip and sides of the tongue.