The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell.

Once the axons pass through the cribriform plate, they terminate and synapse with the dendrites of mitral cells in the glomeruli of the olfactory bulb.

[5] The olfactory epithelium derives from two structures during embryonic development: the nasal placodes, which were long believed to be its sole origin; and neural crest cells, whose contributions have been identified more recently through fate mapping studies.

[9] Neurogenic placodes are transient, focal aggregations of ectoderm located in the developmental region of the future vertebrate head, and give rise to sensory organs.

[11] Early cranial sensory placodes are marked by expression of Six1, part of the Six family of transcription factors that regulate the preplacodal specification.

[9] Development of the olfactory placode requires the presence underlying neural crest-derived mesenchymal tissue.

[12] Continued signaling by BMP, FGF, and RA, the morphogens that initially induced placode formation, collectively coordinate the patterning of olfactory placode tissue into the future distinct cell types that make up the olfactory epithelium.

[21] The olfactory epithelium can be damaged by inhalation of toxic fumes, physical injury to the interior of the nose, and possibly by the use of some nasal sprays.

Because of its regenerative capacity, damage to the olfactory epithelium can be temporary but in extreme cases, injury can be permanent, leading to anosmia.