Pulmonary artery occlusion. II. Morphologic studies.

Abstract

During the 1st wk. following unilateral pulmonary artery occlusion in dogs, the lung develops focal areas of hemorrhagic atelectasis which tend to become confluent and to involve greater amounts of lung parenchyma as the interval between ligation and sacrifice is increased. In the hemorrhagic areas alveoli are filled with red cells and alveolar septae are thickened and infiltrated with macrophages, lymphocytes, plasma cells, and a few polymorphonuclear cells. Although subtle changes in alveolar cell lamellated bodies and in alveolar capillary endothelial cells occur, the extravasation of red cells into alveoli is the most striking change. Other areas of lung remain entirely normal and show no ultrastructural alterations. A few areas of hemorrhagic lung become necrotic, but in most areas the alveoli remain viable.