Tongue. Light micrograph of a section through the surface of a tongue showing a circumvallate papilla (top centre). The papilla is encircled by a deep groove. On the sides of the papilla are numerous taste buds (pale pink, rounded). Below and to the right of the papilla are Von Ebner's glands (light purple). These glands secrete a watery fluid into the groove, which dissolves food components and aids taste reception. Surrouding the circumvallate papilla are filiform papillae (purple), which lack taste buds but contain nerve endings. Mag: x7 when 10cm wide.