What structures are the receptors for sense of smell?

The olfactory receptors are the sensory cells responsible for detecting odours. They are located in the olfactory epithelium, which is a specialised region of the nasal cavity. The olfactory epithelium is made up of three layers: the basal layer, the sustentacular cell layer, and the olfactory cell layer. The olfactory cells are the primary sensory cells of the olfactory system. They are bipolar neurons, meaning that they have two processes, one dendrite and one axon. The dendrites of the olfactory cells extend into the nasal cavity, where they are exposed to odours. The axons of the olfactory cells project to the olfactory bulb, which is located at the base of the brain.