Fig. 1.

The peripheral gustatory system in humans and mice. (A) The location of three types of papillae and the structure of the taste buds. The fungiform papilla (FuP) are distributed over the anterior two-thirds of the tongue, the foliate papilla are located on the lateral sides of the posterior tongue, and the circumvallate papilla (CVP) are mostly located on the center of the posterior one-third of the tongue. Each papilla contains one or more taste buds consisting of four types of taste cells: type I supporting (glial-like) cells, type II receptor cells, type III synaptic cells, and type IV basal (progenitor) cells. (B) The gustatory pathway from the taste buds to the brainstem in humans (left) and mice (right). Taste buds in the FuP are innervated by the chorda tympani, cranial nerve (CN) VII, and the taste buds in the FuP and CVP are innervated by the glossopharyngeal, cranial nerve IX. Taste impulses carried by CN VII and CN IX synapse in the solitary tract nucleus in the medulla oblongata of the brainstem.