Ultrastructure of rabbit tracheal epithelium after the administration of Hexabrix--a hexaiodated contrast agent for tracheobronchography.

The ultrastructure of the tracheal epithelium after the application of 1 ml of Hexabrix (a hexaiodated contrast agent for tracheobronchography) into the airways was studied. Severely altered pseudostratified columnar epithelium was found in the trachea. Eighty-one +/- 5% of the goblet cells had been stimulated to discharged mucus. Forty-three +/- 3% of them were completely exhausted and had degenerated. The ciliated cells displayed marked signs of pathological alteration up to vacuolar degeneration. The ciliary border above the epithelium was severely damaged. The mean number of cilia per micron 2 fell to 3.3 +/- 0.5, but the proportion of intact cilia did not drop below 95%. As morphological signs of impaired self-cleaning ability of the airway epithelium, a large amount of inspissated mucus and numerous bacteria were found in the area of the impaired ciliary border. Coarse grained contrast substance of supreme electron density was intermingled with the condensed mucus. The most pronounced damage to the cells was observed at the sites of direct contact of the contrast agent with the cell membranes.