Fine Structure of Alveolar Areas in the Lung Following Inhalation of ²³⁹PuO₂ Particles

Abstract

Rats exposed to ²³⁹PuO₂ aerosol showed a progressive increase in number and in detachment of type 2 alveolar epithelial cells. Large numbers off lipid droplets were found in septal cells by 30 days. A large exudate comprised of myeloid bodies, cell debris, and a protein-like material was found in the alveolar lumens at 20 days. This stage was followed by an accumulation of histiocytes, which engulfed a large part of the exudate. Destruction of endothelium and accumulation of septal cells, collagen, and elastin were common early findings. Alveolar septa were greatly thickened by 40 days due to edema, connective tissue formation, and accumulation of septal, mast, and plasma cells. Damage to type 1 alveolar epithelium was commonly seen only in the terminal phase of radiation pneumonitis.