Tongue papillae. Light micrograph of a longitudinal section through filiform papillae on the tongue surface. Papillae are the tiny projections that give the tongue its rough texture. The filiform papillae (conical structures) are the most numerous type of papilla. They consist of a surface projection, which is mainly keratin (a structural protein, stained red), and may contain a connective tissue core. They serve a solely mechanical function; other types of papilla are involved in tasting and sensing touch. Magnification unknown.