Tongue papilla. Light micrograph of a longitudinal section through a filiform papilla (conical structure) on the tongue surface. Papillae are the tiny projections that give the tongue its rough texture. The filiform papillae are the most numerous type of papilla. They consist of a surface projection, which is mainly keratin (a structural protein, stained red here), 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: x160 at 35mm size.