Publication Type Academic Article
Authors Kawanami O, Matsuda K, Yoneyama H, Ferrans V, Crystal R
Journal Acta Pathol Jpn
Volume 42
Issue 3
Pagination 177-84
Date Published 03/01/1992
ISSN 0001-6632
Keywords Bronchi, Endothelium, Vascular, Pulmonary Alveoli, Pulmonary Fibrosis
Abstract A light and electron microscopy study was performed on endothelial cells of alveolar capillaries in biopsied lung tissues obtained from 28 patients with interstitial fibrotic lung diseases, including idiopathic pulmonary fibrosis, sarcoidosis, hypersensitivity pneumonitis, chronic eosinophilic pneumonia, collagen vascular diseases and acute interstitial pneumonia. In the relatively early stages of acute interstitial pneumonia, hypersensitivity pneumonitis and other diseases, the cytoplasms of the endothelial cells appeared swollen and electron-lucent and occasionally showed degeneration and necrosis. Although mitosis was not evident in the endothelium at any disease stage, some capillary endothelial cells showed regeneration. Furthermore, although rarely, they showed obvious phenotypic transformation into diaphragmed fenestrae in some limited segments of fibrotic lungs in the 20 of the 28 patients examined. The frequency of endothelial fenestration seemed to be correlated with the degree of interstitial fibrosis along the alveolar walls. In such fibrotic lung tissues, cuboidal metaplastic cells of bronchiolar origin proliferated on the luminal side. The mechanism of endothelial fenestration in the alveolar capillaries is assumed to be comparable with cuboidal metaplasia of alveolar epithelial cells. The alveolar capillary endothelium is recruited from the bronchiolar capillaries via bronchopulmonary anastomoses unless endothelial repair occurs in situ. Regenerating endothelial cells move into the alveolar capillary tubes along the remnant sleeves of the basement membrane. New endothelial processes finally display their original fenestrated structure while secreting irregular fragments of basement membrane during implantation in the capillary beds.
DOI 10.1111/j.1440-1827.1992.tb01669.x
PubMed ID 1570740
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