Abstract

Chronic bronchiolitis is a condition associated with cigarette smoking, and later associated with pulmonary parenchymal alteration and progressive deterioration of lung function. Early respiratory bronchiolitis was produced in Sprague-Dawley rats by indirect inhalation of cigarette smoke daily in a smoke exposure chamber designed by authors for 1 month. Experimental group A (n=5) was sacrificed after having smoked 30 cigarettes, group B (n=5) after 80 cigarette, and group C (n=7) after 140 cigarettes, respectively. Examination of morphologic changes in the lungs was done on light microscope, transmission and scanning electron microscopes. Light microscopically, increase in number of goblet cells in the bronchial mucosa, brown-pigmented macrophages in the alveoli, multifocal alveolar collapse adjacent to the bronchioles, dilatation of alveolar ducts and alveolar spaces were observed. Transmission electron microscopically, irregularly shaped Clara cells, alveolar wall collapse, and focally type I epithelial cell injury were seen. Scanning electron microscopically, scattered alveolar collapse, irregular dilatation of alveolar ducts, alveolar spaces and interalveolar pores (pores of Kohn) were seen. The terminal and respiratory bronchioles showed morphological alteration of Clara cells, but no evidence of cellular bronchiolitis or bronchiolar obstruction. We conclude that sidestream smoke induces an early respiratory bronchiolitis including aggregates of brown pigmented macrophages and varying degrees of structural alteration of adjacent pulmonary parenchyma.

• Keywords: Sidestream smoke;Respiratory bronchiolitis;Transmission and scanning electron microscopy;