Objective To study the pathological characteristics, pathogenesis and the pathogen of severe acute respiratory syndrome (SARS) by systematic examination of the pathological changes in 30 organs from 6 autopsies of patients dying in different periods of the disease. Methods Pathological changes were studied by light microscopy, electron microscopy, histochemical and immunohistochemical staining. Results ①The basic pathological changes in the patients dying at the early stage of SARS were mainly degenerative changes, such as cellular degeneration, apoptosis and necrosis in the lung and immune organs (spleen, lymph nodes, and mucous membrane lymph tissue), and circulatory disturbances such as pulmonary edema, hyaloid membrane formataion and hemorrhage. In the patients dying at the middle and later stages, the basic pathological changes were necrosis and excoriation of pulmonary alveolar epithelial cells, interstitial fibrotic proliferation, accompanied by early fibrosis and progressive atrophy of lymphoid tissues. These results confirmed again that the lung and immune organs were the major target organs. ②The process of pulmonary changes could be divided into three periods: the first period was characterized by acute exudative and leakage inflammation (within two weeks of onset of the disease, the main pathological changes were severe diffuse edema and hyaline membrane formation in lung), the second period showed the feature of pulmonary epithelial necrosis and excoriation, accompanied by hyperplastic and organizational inflammation (within third to fourth weeks); the third period was hyperplasia and early fibrosis of pulmonary tissue (within fifth to sixth weeks) . The lung damages were widespread, immediate, progressive, staged and diverse. ③Serious damage and diffuse hemorrhage were observed in the immune organ, such as spleen, lymph nodes. Remarkable atrophy was seen in spleen nodules and lymph folliculi, with early apoptosis and necrosis of lymphocytes. The number of T cells and B cells were extremely decreased; the immune function became very low. The damages to the immune organs were widespread, immediate, and persistent. ④It was confirmed that novel coronavirus(Co v) was the major pathogen, and the chlamydia like particles was also one of the pathogens. At the same time, unknown stick like structures were found in the lung and spleen, and cocci were also found in the lung. Conclusions Examinations of the autopsy specimens from SARS patients showed that the pathogens were diverse, in which Co v was the major pathogen. The pathology involved multiple organs and cells in the human body, producing viremia. The lung and lymphoid tissues were the main target organs; pathological changes of the lung were progressive and could be divided into 3 stages. Pulmonary fibrosis occurred in 4～6 weeks. The atrophy of the immune organs was persistent and progressive. The immune function was low for a long time(The pictures were put into the color pages of this journal.).

To investigate changes in density of platelet glycoprotein (GP)Ⅱb/Ⅲa receptor during the perioperative period of hepatectomy in rats with myocardial infarction. 26 adult SD rats were randomly divided into 2 groups: the control group(1)( n =13) and the infarction group(2)( n =13). Myocardial infarction was produced by celiac injection (1 time/d) of isoproterenol (30mg/kg) for 3 days. All rats underwent hepatectomy after 3 weeks. Platelet surface density of GPⅡb/Ⅲ receptors was determined by flow cytometric analysis before and 6, 12, 24, 48, 72 hours after the operation. 12 hours after the operation, the density of GPⅡb/Ⅲa was transiently increased compared with preoperative period in control group ( P