A quantitative light and electron microscopic study of hamster tracheal epithelium with special attention to so-called intermediate cells.

Epithelial cells of the lower trachea of the hamster were studied and quantified by high resolution light microscopy and electron microscopy. The epithelium was composed of basal cells, secretory cells, and ciliated cells; preciliated cells were extremely rare in the undisturbed epithelium. In addition, a few cells were of indeterminate character. Correlative light and electron microscopy indicated that about 10% of the basal cell population, categorized by light microscopy, was composed of the nucleated basal portions of tortuous secretory cells. Electron microscopy revealed that the light microscopic indeterminate category was heterogeneous, being composed of several cell types, including secretory cells with scant secretion granules, some "tall" basal cells, and very few cells that were truly indeterminate. Furthermore, review of the literature and the results of this study indicated that several different cell types, including secretory cells with sparse secretions and preciliated cells, have been previously called "intermediate cells." The study focuses attention upon the difficulties in accurately classifying certain types of tracheal epithelial cells, especially at the light microscopic level.