Fig. 2.

Chemoresponsive cells that express elements of the taste transduction cascade are present throughout the respiratory system as well as in taste buds. Despite similarities in molecular characteristics, these chemoresponsive cells are not identical. We distinguish at least 3 types of chemoresponsive cells within the respiratory system: 1) solitary chemosensory cells (SCCs) distributed within the anterior nasal epithelium, 2) microvillous cells, within the olfactory epithelium, and 3) brush cells in the trachea. Each of these cell types has a distinctive morphology and different relationships to the afferent nerve fibers in the vicinity. Below: Semischematic diagrams of the 3 TrpM5+ cell types showing differences in morphology and relationship to local nerve fibers.