Fig. 9

H&E section of (a) a lung alveolar cell hyperplasia and (b) a bronchiolo-alveolar cell adenoma in rats treated with 1.0 mg MWCNT-A and 1.0 mg MWCNT-B, respectively. In the region of hyperplasia in panel A, the bronchiolo-alveolar architecture is readily detectable with round to oval or cuboidal alveolar Type II cells with abundant eosinophilic cytoplasm prominently outlining the alveolar walls forming a single layer that is continuous throughout the area of hyperplasia. In the adenocarcinoma shown in panel B, the underlying alveolar architecture is obscured to various degrees, and there is a sharp demarcation of the area with high epithelial density from the surrounding tissue. For a more in-depth discussion of these lesions, see Ref [22]