Distribution of choline acetyltransferase (ChAT) immunoreactive nerve fibers in the nasal mucosa; especially in the respiratory epithelium

The distribution and morphological construction of cholinergic nerve fibers in the respiratory nasal mucosa of the rat and human were investigated using choline acetytransferase (ChAT) activities by means of light microscopy, confocal laser scanning microscopy and electron microscopy. It was observed that ChAT-immunoreactive (IR) nerve fibers were distributed to form fine varicosities around the blood vessels and seromucous glands under the epithelium and at the basement membrane and within the epithelium. Electron microscopy showed that the ChAT-IR nerve fibers within the epithelium terminated as free nerve endings. Some of them were in close contact with goblet cells. The distribution of ChAT immunoreactive fibers resembled that of vasoactive intestinal polypeptide-IR nerve fibers.