Pathologic Alterations in Lung Injury and Pulmonary Fibrosis Induced by Endotoxin and Bleomycin

Objective: To study the pathologic changes in lung injury and pulmonary fibrosis induced by endotoxin and bleomycin.Methods: Sixty rats were separated into three groups at random as endotoxin group,bleomycin group,and control group according to the intratracheal or via caudal vein injection of endotoxin,bleomycin,and normal saline respectively.Five rats from every group were sacrificed on the 3rd,7th,14th,and 28th day to observe the pathologic changes in lung tissue by using transmission electronic microscope.Results: In endotoxin group,the degree of alveolitis was severe.Alveolar epithelium cells type Ⅱ(ATⅡs) showed edema in the mitochondrion and degranulation of osmiophilic lamellar body,but hyperplasia was not obvious.In bleomycin group alveolitis was observed that happened slowly and developed into progressive pulmonary fibrosis,and ATⅡs were necrotic gradually.Deposition of collagen fibres around the mesynchemal cells were also present.Conclusion: Both endotoxin and bleomycin could cause pulmonary injury,and the former could recover,but the later would develop into progressive pulmonary fibrosis.This may be related to the degree of ATⅡ injury.