Olfactory epithelium

A sense of smell permits us to detect noxious gases, and spoilt food, motivates eating, and might play a section in the sexual attractiveness. The olfactory epithelium lies in the dorsal nasal cavity. It contains bipolar olfactory receptor neurons (ORNs) and supporting cells. A dendrite appears from the ORN and expands to the surface of the epithelium to form a cluster of 6–12 immobile olfactory cilia. Such extend into a layer of mucus secreted by the supporting cells. The central directed unmyelinated axon of the ORN runs via the olfactory (cranial I) nerve to synapse with cells in the olfactory bulb. The human olfactory epithelium contains around 10⁸ ORNs.