Fig. 1.

The morphology of rat lung tissues exposed to hypoxia for 1, 3, and 7 days. Control group: alveolar and pulmonary interstitial structure was normal without liquid exudation. Hypoxia-1 group: alveolar wall structure was normal, but there were some areas of telangiectasia congestion and mild pulmonary wall thickening of small arteries. Hypoxia-3 group: there were widening of alveolar wall, focal emphysema, focal alveolar hemorrhage, and slight thickening of the small arterial wall in the lungs. Hypoxia-7 group: the alveolar cavity was obviously deformed and smaller, the interstitial thickening and enlargement of the pulmonary interstitium, thickening of the small arterial wall, and the telangiectasia and congestion were obvious. HE staining (× 400)