Light micrograph of vertical section of a tongue showing papillae. 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.