Correlative histological and ultrastructural study of unusual changes in human tracheobronchial epithelium.

In tracheostomy patients with chronic bronchitis, scanning electron microscopy reveals detailed surface changes in the tracheobronchial mucosa. The principle of intermicroscopic correlation, i.e., the sequential examination of a specimen by different microscopic procedures, is illustrated with giant cilia. After re-embedding the scanning electron microscopic specimens and precisely locating a ciliary convolution by light microscopy in semithin section, the giant cilia were studied in ultrathin sections by transmission electron microscopy. The cilia were shown to be at least 9 microns long (normal ciliary length = 4-6 microns). Central and peripheral microtubular axonemal structures with a 9 + 2 arrangement were clearly shown in both longitudinal and cross section. Giant cilia, thus, most closely resemble outgrowths of normal cilia. If they are motile at all, they seem unlikely to effect a transport function coordinated in direction and time.