title: Sequential changes in lung morphology during the repair of acute oxygen-induced lung injury in adult rats.
abstract: We studied changes in lung ultrastructure and collagen content during the repair of acute lung injury in adult rats exposed to 100% O2 for 60 h and recovering in ambient air. In the interstitium, during the first 3 days of repair, the number of neutrophils decreased 16-fold, and monocytes and lymphocytes increased to 7-fold and 4-fold the respective control values. Myofibroblasts increased about 5-fold and the volume of the interstitial matrix remained high. By 7 days, the differential count of inflammatory cells was normal although the number of total interstitial cells and myofibroblasts decreased more slowly. In the capillary endothelium, after 3 days of repair, the cells were hypertrophied and had organelle-rich cytoplasm, and total cell number had increased back to control values; endothelial cell number increased an additional 63% between 3 and 7 days of repair. In the epithelium, type 2 cells increased 150% during the first 3 days of repair before decreasing; type 1 cell number did not change. After 28 days of repair, the lungs appeared qualitatively almost normal; however, interstitial cell number and collagen content were still increased. We conclude that the repair of oxygen-induced lung injury involves a complex pattern of morphologic changes that has important similarities to those occurring during repair on other tissues such as the skin.
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D008168:Lung / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010100:Oxygen / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D003094:Collagen; D010100:Oxygen