Quantitative evaluation of the degree of damage to tracheal epithelium.

Quantitative evaluation of the injury to the tracheal epithelium was carried out under various experimental conditions. The damage of the epithelium was classified in three groups, according its severity. In several impaired epithelium all the goblet cells were stimulated to release their secretion. The mechanism of mucus discharge was maximally accelerated. Over 90% of the exhausted goblet cells degenerated. In average only 1 cilium/micron 2 was left in the ciliary border. Over 10% of the remaining cilia displayed signs of alteration. As morphological signs of impairment of the self-cleaning ability of the epithelium, large amounts of inspissated mucus and numerous bacteria were observed in the area of the damaged ciliary border. In moderately severe epithelial injury about 80% of the goblet cells were stimulated and half of them degenerated. The mean number of cilia in the ciliary border was 3/micron 2. The signs of impairment of the self-cleaning ability of the epithelium were less pronounced. In mild damage, about half of the goblet cells were stimulated and the degenerated ones formed less than 10% of all the mucous-secreting elements. The number of kinocilia per micron 2 fell on the average by one third. No signs of the self-cleaning ability impairment were recorded.