Morphologic Study of Bleomycin-induced Pulmonary Fibrosis in Rats

Objective To observe the morphologic change of bleomycin induced pulmonary fibrosis in rats and to explore its pathogenesis. Methods SD rats in good conditions were divided into two groups at random:control group ,model group. On experimental day(day 0),the rats were intratracheally instilled with bleomycin(5mg/kg body weight). On days 1,3,7,14,28 after instillation ,six rats of each group were sacrified and the lungs were harvested for histopathological examination and determinations of hydroxyproline(HYP). Results Lung lesions were mainly alveolitis on days 1-7 after bleomycin administration and advanced to the chronic stage of pulmonary fibrosis after day 14. On days 3-7, alveolar typeⅠcells were degenerated broken down and desquamated. Endothelial cell swelled and alveolar typeⅡcells became hyperplastic. The number of alveolar typeⅡcells decreased in days 14-28. Myofibroblasts,fibroblasts, collagen were hyperplastic. The content of HYP in lung tissue was increased significantly. Conclusion Bleomycin\|induced pulmonary fibrosis in rats was mainly alveolitis on days 1-7 after bleomycin administration and advanced to the chronic stage of pulmonary fibrosis after day 14.