Foetal mouse tongue. Coloured scanning electron micrograph (SEM) of the tongue of a mouse foetus that is near term (when it will be born). The tongue will be covered in tiny projections (papillae) when it is fully developed. Only the fungiform papillae (round lumps, purple) are seen at present. These are associated with the taste buds (not seen) that transmit sensory taste input to the brain. Other papillae, such as the more numerous filiform ones, will develop later, imparting a rough feel to the tongue. A third papilla type, the circumvallate papillae (not seen), will also have taste buds associated with it. Magnification: x100 at 6x7cm size.