Nasal Epithelium: Structure and Function

The nasal cavity is lined by pseudostratified ciliated columnar epithelium (respiratory epithelium) containing:

• Ciliated cells: Beat in coordinated waves to move mucus toward nasopharynx (mucociliary clearance).
• Goblet cells: Secrete mucins (MUC5AC, MUC5B) forming the gel layer.
• Basal cells: Stem/progenitor cells for epithelial renewal.
• Brush cells, small granule cells, olfactory neurons (superior region).

Functions

• Air Conditioning: Warms, humidifies, filters inspired air.
• Defense: Mucociliary escalator traps and removes particles, pathogens, allergens.
• Immune Surveillance: Epithelial cells express TLRs, produce defensins, cytokines, IgA.
• Olfaction: Specialized neuroepithelium in superior turbinate/septum.

Clinical Relevance

• Ciliary dyskinesia (primary ciliary dyskinesia) → chronic sinusitis, bronchiectasis.
• Epithelial metaplasia (squamous) from chronic irritation (smoke, pollution) → loss of clearance.
• Target for intranasal vaccines and drug delivery.