Ultrastructural Alterations of Alveolar Tissue of Mice

Abstract

Young mice (4 days and 1 and 2 months old) were exposed to 0.6 to 1.3 ppm (1.4 to 2.8 mg per cu m) ozone for six to seven hours per day for one or two days. The morphological changes seen in the alveolar cells were both age- and dose-dependent; most sensitive were the youngest mice (4 days old) exposed for two days. The endothelial cells lining the small capillaries appeared to be the main target of the ozone. In many sections the lining membranes were broken and fragmenting. The basement membrane was usually intact. Some erythrocytes were disrupted. Infrequently the blood-air barrier was completely broken. Cell debris was often present in the alveoli as well as the capillaries. Some disorganization of the cytoplasm of the large alveolar corner or wall cells was evident. Less extensive morphological change was seen in the older animals exposed for one day.