The ultrastructure of the tracheal epithelium was studied 5 min after intratracheal administration of 0.5 ml triiodinated contrast agent (Iomeron, Bracco-Byk Gulden GmbH). Tracheae of the experi- mental rabbits were lined with a pseudostratified columnar ciliated epithelium. The apical juncti- onal complexes were intact; the intercellular spaces remained narrow. The ciliated cells revealed only slight signs of pathological alteration. The goblet cells appeared as isolated elements in the epithelium. 33 ± 4% of them discharged their secretion. The mechanism of mucus evacuation was accelerated. 40 ± 2% of the secretory cells were represented by completely exhausted, degenerated elements. In the slightly altered ciliary border, 9.3 ± 0.5 of kinocilia per 1 mm 2 were encountered. The altered cilia represented 2.2 ± 1.8%. As a sign of impaired self-cleaning ability, clumps of condensed mucus were noticed in some areas of the ciliary border. The contrast agent was not discovered in the mucous membrane of the airways. According to our classification, the damage of the airway epithelium due to the intratracheal administration of 0.5 ml of Iomeron was slight.

        Key words: contrast agent - iomeprol - ultrastructure - trachea