Fig. 2
From: Cobalt nanoparticles induce lung injury, DNA damage and mutations in mice
Histological changes in lungs of mice 7 days and 4 months after metal nanoparticle exposure. Mice were instilled intratracheally with 50 μg per mouse of Nano-Co or Nano-TiO2. Control mice were instilled with physiological saline. Lung sections collected from mice 7 days (a–d) and 4 months (e–h) after exposure were analyzed by H&E staining (a–g) or trichrome staining (h). a & e show normal lung parenchymal structure in control mice. (c & d) show severe acute lung inflammation at day 7 after Nano-Co exposure, which was reflected by infiltration of a large amount of neutrophils and macrophages into the alveolar space and septa, focal alveolar epithelial cell hyperplasia, and thickening of the alveolar wall. Arrow in (c) shows a mitotic hyperplastic alveolar epithelial cell, which was enlarged at the top right corner of (c). g shows extensive interstitial fibrosis and bronchiolization of the alveoli (arrows in g) in the lungs of mice at 4 months after Nano-Co exposure. h shows increased collagen deposition (blue staining) in the alveolar septa by trichrome staining. However, Nano-TiO2 instillation did not cause these effects (b & f). Scale bar: 50 μm