Fig. 1

Microscopic changes in the lung tissues of patients who have died from COVID-19 (staining with hematoxylin and eosin). A Diffuse alveolar damage in the acute stage; the walls of the alveoli are filled with dense eosinophilic masses of fibrin, hyaline membranes (arrows); in the lumen of the alveoli, you can observe individual filaments of fibrin. B Diffuse alveolar damage in the acute stage, the lumen of the alveoli is filled with fibrin filaments, single erythrocytes, cells of the respiratory epithelium, and polymorphonuclear leukocytes. C Diffuse alveolar damage in the acute stage, round and oval cells almost completely filling the lumen of the alveoli. D Proliferation of type II alveolocytes leads to the formation of bizarre epithelial structures. Scale bars A, C, D—100 μm, B—50 μm