Fig. 1.

Histological assessment and collagen content in lung tissue during the time course of bleomycin-induced lung fibrosis. A–F: representative light micrographs in lung tissue sections of saline- and bleomycin-instilled mice stained with hematoxylin-eosin. A: saline-instilled mouse. B–F: bleomycin-instilled mice at 1, 4, 8, 12, and 16 wk, respectively. Scale bars indicate 50 μM. Histopathology shows dense areas of lung fibrosis at 4 wk (C) with a more severe and diffused fibrotic reaction at 8 wk (D). At 12 wk (E) there was a focal and markedly less-pronounced fibrosis and at 16 wk (F) most areas of the lung parenchyma were preserved. G: fibrosis score. Data are expressed as means ± SD (n = 6–9 mice in each time point). H: total lung collagen levels were measured by hydroxyproline content (n = 6–9 mice in each time point). Red points represent mice selected for microarray analysis. *P < 0.05; **P < 0.001.