Alveolar septal changes in pulmonary edema: a subcellular study of lung clearance in the dog.

: Left lobe lung biopsies were obtained in dogs allowed to breathe in atmospheres of coal or barium sulphate dust before ligature of the left pulmonary veins and at 15 min, 1, 5, 7, 15, and 30 days after ligature. All samples were prepared for transmission electron microscopy (TEM) and scanning electron microscopy (SEM); in addition, samples from the barium sulphate group were examined by electron diffraction analysis (EDA). Two main phagocytic cell types were identified. In addition lymphatic capillary-like structures were observed in the alveolar septum after ligature of the pulmonary veins.