Endothelial cell changes in acute hepatitis. A light and electron microscopic study.

Hepatic endothelial cells were studied by light and electron microscopy in 48 patients with acute hepatitis due to virus infection or drug idiosyncrasy. Light microscopy revealed cell swelling and appearance of dense refractile intracytoplasmic granules staining with the amylase PAS reaction and for iron by Perls' method. They were orcein-negative. These cells, regarded as 'activated' endothelial cells, were found throughout the parenchyma, especially in the classical form of acute hepatitis. In acute hepatitis with bridging, panacinar or periportal necrosis, activated endothelial cells were prominent in the necrotic areas. They were constantly seen lining newly formed capillaries in these sites. By electron microscopy, the intracytoplasmic granules had the characteristics of primary or secondary siderosomes. In areas of capillarization, basement membrane material was seen on the aspect of the activated cells facing the space of Disse. Activated endothelial cells may play a part in protecting hepatocytes from injury.