ABSTRACT
A sense of smell allows us to detect spoilt food and noxious gases, motivates eating, and may play a part in sexual attractiveness. The olfactory epithelium lies in the dorsal nasal cavity. It consists of bipolar olfactory receptor neurons (ORNs) and supporting cells. A dendrite emerges from the ORN and extends to the surface of the epithelium to form a cluster of 6-12 immobile olfactory cilia. These extend into a layer of mucus secreted by the supporting cells. The centrally directed unmyelinated axon of the ORN runs through the olfactory (cranial I) nerve to synapse with cells in the olfactory bulb. Human olfactory epithelium contains about 108 ORNs.
