Olfactory mucosa

The part of the nasal cavity that is lined with olfactory mucosa is known as the olfactory region (pars olfactoria tunicae mucosae nasi), while the rest of the nasal cavity that is lined by ordinary respiratory mucosa is known as the respiratory region.

Structure

Olfactory mucosa lines about 5cm² of the posterosuperior parts of the lateral nasal wall. Parts of the nasal cavity lined by olfactory mucosa include: parts of the roof of the nasal cavity, the superior nasal concha and some upper parts of the middle nasal concha, parts of the nasal septum, and the sphenoethmoidal recess.

The olfactory mucosa is thicker and lighter in colour (yellowish-brown) in comparison to the (pinkish) respiratory mucosa lining the rest of the nasal cavity.

Glands of the olfactory mucosa secrete a mostly serous fluid.

Histology

The olfactory mucosa consists of the olfactory epithelium and the underlying lamina propria, connective tissue containing fibroblasts, blood vessels, Bowman's glands and bundles of fine axons from the olfactory neurons.

In vertebrates, the olfactory epithelium consists of a three basic cell types: bipolar olfactory receptor neurons; sustentacular cells, a type of supporting cell; and basal cells, the stem cells that continuously give rise to new olfactory receptor neurons and sustentacular cells.

Electron microscopy studies show that Bowman's glands contain cells with large secretory vesicles. The exact composition of the secretions from Bowman's glands is unclear, but there is evidence that they produce odorant binding protein.