[An electron microscopic study of the pulmonary alveolar capillaries in idiopathic interstitial pneumonia and lungs of collagen vascular diseases].

The ultrastructure of pulmonary alveolar capillaries in idiopathic interstitial pneumonia (IIP) and collagen vascular diseases (CVD) were investigated. In IIP, the endothelial cells were only slightly swollen. The basement membrane (BM) was moderately thickened. In CVD, swelling of the endothelial cells and thickening of the BM were more severe than those of IIP. The injury of the endothelial cells seemed to be more severe than IIP. The patients with PSS and MCTD revealed degeneration of endothelial cells as well as lamellation of BM. The endothelial cell damage was most severe among CVD cases, and these changes were assumed to induce pulmonary hypertension. Microtubular structures were observed in the endothelium of SLE, dermatomyositis, polymyositis, PSS and MCTD patients. Weibel-Palade bodies and increase of pericytes were noticed in PSS and MCTD patients which seemed to be related to endothelial injuries. No electron-dense deposits were observed in any case.