1986 Volume 21 Issue 2 Pages 115-122
A histopathological study was performed on Wistar male rats exposed to 10 ppm nitrogen dioxide for two weeks in order to observe the effects of nitrogen dioxide upon pulmonary alveoli.
Histological changes of the lungs were clearly observed in a short period of time after the exposure to nitrogen dioxide: On the 3rd day, irregular blebing of the cytoplasm and small vacuoles in the cytoplasm of the Type I alveolar cells were observed: On teh 7th day, the blebing enlarged to become cyst-like structures, and Type I alveolar cells desquamated from the basement lamina: The Type II alveolar cells increased in numbers with prominent vacuolar degeneration, disappearance of cell organelles and concentration of the nuclei. Transformation of Type II to Type I alveolar cells can not be observed even on the 14th day.
The changes in the capillary endothelial cells of the alveolar walls were as follows: On the 3rd day, the distinguished increase of the pinocytotic vesicles was observed: On the 7th day, vacuolar degeneration appeared in some parts: On the 14th day, the separation of cells from the basement lamina and the detachment of the junction of endothelial cells with the leakage of erythrocytes through the intercellular spaces were observed. The edema in the pulmonary interstitial tissue appeared 3 days after the exposure, which was clearly observed on the 14th day.
In tracheal and bronchial walls, goblet cells marked increased in numbers and its mucus content increased 3 days after the exposure. Seven days after the exposure, proliferation of non-ciliated epithelial cells in terminal bronchioles was observed. There was a mild degree of inflammatory cell infiltration in some parts of the tracheal and bronchial walls, and 14 days after the exposure, the increase of reticular fibers in submucosa was seen.
