Immunostaining of airway afferent nerves for PGP9.5 (green, Alexa Fluor 488). Nerves that gave rise to varicosities in the epithelial plexus are associated with nerve branches located superficially near the epithelial basement membrane (arrowheads). Varicose epithelial fibers (arrowheads) were arranged into extensively branched arboreal structures from a central point (asterisk). From right lower lobe biopsies.