Functional diversity of taste cells. A review

Our ability to sense chemicals occurring in food and beverages relies on the operation of specialized epithelial cells called taste cells, found as clusters (taste buds) mainly in the oral cavity. Unlike other sensory cells, such as hair cells in the cochlea, taste cells differ from each other in terms of structural features. At least three main morphotypes are now recognized in mammalian taste buds: Type I, Type II and Type III. Each of them displays specific membrane properties (i.e. ion channels and receptors) as well as intracellular signalling pathways. Some of themare electrically excitable (Type II and Type III), whereas Type I seems to subserve a glial‐like role. They also differ in theway they communicatewith nerve terminals: apparently, only Type III cells seem to be able to relay directly information via synaptic contacts, whereas the other types of cells may communicate through less specializedmechanisms, including ATP release through non‐conventional synapses.What is then thesignificance of these three cell types in the context of taste reception? Although it is not yet possible to draw any definitiveconclusion, the emerging view is that functional diversity of taste cells might represent the basis for a ‘sensory processing’circuitry designed to detect chemicals, as a whole.