Ultrastructural organisation of intraepithelial nerves in the human airway tract.

Intraepithelial nerves of human airway tract were studied by electron microscopy after conventional glutaraldehyde fixation. Specimens were obtained from five patients at three different airway levels--the trachea, the right upper lobe bronchus, and segmental bronchus. Intraepithelial axon profiles were located either near the basement membrane or close to the lumen but were rare in the intermediate area of the epithelium. Axon profiles close to the lumen were seen only in the central airways (levels 1 and 2), while profiles close to the basement membrane were seen in all three levels.