For some unknown reason, the exit space from the back of the nasal cavity is larger in women than in men. Also, the olfactory membrane is pigmented. No one knows why, but we do know that the pigmentation does play a role in olfaction, because albino animals lack a sense of smell. The olfactory membrane, or epithelium , is a layer of cells on the roof of the nasal cavity. Supporting cells are similar to glial cells and help produce mucus.
Basal cells are the source of new receptors.
Olfactory receptor cells, actually neurons, are the site of transduction. The size of the epithelium is a good indicator of the acuity of an animal's sense of smell. When we inhale, most of the chemical stimuli in the air are dissolved in the layer of mucus coating the epithelium. This mucus contains water, mucopolysaccharides, antibodies, enzymes, salts, and odorant-binding proteins . Olfactory receptor cells are bipolar, meaning that they have one dendrite and one axon.