Population and ultrastructural changes in murine alveolar cells following 239PuO2 inhalation.

Early changes affecting the principal cellular components of pulmonary alveoli after inhaling 239plutonium dioxide were followed by quantitative and qualitative electron microscopy in mice and rats. Different accumulated doses of a irradiation were achieved. The numbers of alveolar macrophages and interstitial mononuclear cells rose in mice especially after a higher dose of radiation, whilst in rats interstitial fibroblasts were increased. The evidence from mice suggested pronounced secretory activity of type II epithelial cells with subsequent uptake of phospholipid by alveolar macrophages, which developed large cytoplasmic inclusions, but rats were much less severely affected. Pneumonitis was not a feature and with the dosage of radiation employed endothelium escaped structural damage. Sensitivity between species differed, both according to cell type and to intensity of exposure, so demanding caution in the application of experimental findings to man.