Abstract
Ultrastructural localization of inhaled submicron lead fume was studied on the lungs of rats. The specimens were obtained from two series of experimental exposure to metallic lead fume of 0.3μ in projected diameter (σg 1.31, AMD= 1.1μ) in concentra-tion of 120mg/m3 in the first experiment and 0.04 μ in projected diameter (σg 1.40, AMD= 0.19μ) in concentration of 10mg/m3 in the second experiment respectively.
Qualitative identification of lead nature of the fine particles deposited in the tissue was parformed with the aid of X-ray micro-analyzer equipped with energy dispersive type detector.
Aside from usual aboundant accumulation of particles in the alveolar macrophage, widespread uptake of lead particles was common findings in the epithelial cells cover-ing the bronchial tree as well as the alveolar surface. In the bronchial epithelium, particles were found more frequently in the periphery, especially in the terminal region, in which non-ciliated cells contained more numerous particles than ciliated epithelium. In the alveolar wall both the type I and type II alveolar epithelium contained lead particles. In every type of the above cells, phagosomes and lysosomes were the main site of localization of particles. Deformation and degradation of fume particles were conspicuous in the cytoplasm especially in the lysosomes and their in-tercellular biological solubilization were suggested. Significance of the above findings was discussed in relation to possible mechanisms of onset of cellular injury in the respiratory tract.
