Nasal cavities: Olfactory epithelium

Olfactory neurons constitute up to 50% of the cells in the epithelium. They are bipolar neurons that span the epithelium; their nuclei are generally located in the mid to lower regions of the epithelium. Dendrites extend apically, ending in an olfactory vesicle from which numerous, odorant-detecting, non-motile cilia extend. Axons from olfactory neurons form fascicles that pass through the cribriform plate to enter the olfactory bulb of the brain. Collectively, they form the olfactory nerve (cranial nerve I).

Cilia on olfactory neurons are non-motile and express odorant receptors specific for each neuron. They extend from a knob-like swelling at the end of the dendrite called the olfactory vesicle

Supporting (sustentacular) cells are columnar cells that also span the epithelium. They possess microvilli and their nuclei are generally located in the upper portions of the epithelium. Sustentacular cells provide physical and metabolic support for the neurons, similar to glial cells in the brain.

Basal cells are progenitor or stem cells, resupplying the epithelium with olfactory neurons and supporting cells. The turnover rate for olfactory neurons is around 30-60 days, with some potentially surviving up to 6 months.

Basal cells are progenitor or stem cells, resupplying the epithelium with olfactory neurons and supporting cells. The turnover rate for olfactory neurons is around 30-60 days, with some potentially surviving up to 6 months.

This image was taken of a slide in the University of Colorado collection.