Distribution and origin of nitric oxide synthase-containing nerve fibers in human nasal mucosa.

Human nasal mucosa was investigated by nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry. NADPH-diaphorase-positive fibers were distributed around blood vessels and seromucous glands, but none was seen in the respiratory epithelium. The pterygopalatine ganglion was then studied to determine the origin of these fibers, and many neurons were found to be labeled. These labeled neurons (86.2%) consisted of small (14.7%), medium-sized (18.4%) and large cells (53.1%). These results suggest that nitrinergic nerve fibers may originate from the pterygopalatine ganglion and that nitric oxide may play some role in the nervous control of the human nasal mucosa.