Bronchiolar pathology. II. Light and electron microscopical changes of bronchiolar epithelial cells in rabbits...

Intratracheal administration in rabbits of a detergent solution (Blue Perlan) determined the progressive swelling of bronchiolar epithelial cells, mainly of non-ciliated secretory ones, with hypertrophy of cytoplasms, frequent bleb ruptures and partial cell necroses. Mucoprotein synthesis was not enhanced. Ultrastructurally, the non-ciliated Clara cells were predominating; their cytoplasms were hypertrophied, prominent in bronchiolar lumina, and contained a few mitochondria and numerous dark-stained secretory granules with a thin membrane; glycogen was present in cytosol, and the apical zones of cytoplasms were locally balloonized; nuclei were chromatin-monomorphous and had an evident membrane. Disrupted blebs presented the same granules and glycogen-rich structure as the cytoplasms. Intermingled ciliated cells presented small mitochondria, sometimes modified, and some secretory granules; cilia and basal corpuscles were rarely damaged. Some microvilli intermingled among cilia, but they were extremely rare in non-ciliated secretory hypertrophied cells. Some tight junctions were observed between bronchiolar cell cytoplasms. The evolution to partial necrotizing bronchiolitis was obvious mainly after the third intratracheal injection of the detergent solution.