Ultrastructure of the tracheal epithelium in rabbits after acetylcholine administration.

The ultrastructure of the tracheal epithelium was studied 5 and 20 min after intravenous (i.v.) administration of 0.5 mg of acetylcholine. As a result of this treatment, the goblet cells were overstimulated and damaged, and the mechanism of their secretion was accelerated. Only a mild pathological alteration was encountered in the ciliated cells. According to our classification, the degree of secretory element damage was severe, the injury to the ciliary border was moderate. The morphological signs of the severe impairment of the self-cleaning ability of the epithelium were inspissated mucus and very numerous bacteria in the area among free cilia.