Tongue papillae capillaries. Coloured scanning electron micrograph (SEM) of a resin cast of capillaries in the papillae of the tongue. Capillaries are the smallest blood vessels. Each upwards projection shows where a capillary extends into a papilla. The papillae project from the tongue's upper surface, giving it its rough texture. The most numerous tongue papillae are the filiform papillae, which do not contain taste buds. It is in the capillaries that nutrients and gases are exchanged with the tongue tissue through the permeable capillary walls. The cast was made by injecting resin into the blood vessels. The surrounding tissues were then chemically digested.