Lung histopathology. Aspect of alveolar walls 60 minutes after IV injection of PBS (A) or 10 μg of MWReg30 (B); (C) 24 hours after IV injection of 10 μg of MWReg30; (D) vascular engorgement of septal capillaries with erythrocytes, 20 minutes after IV injection of 100 μg of MWReg30. (A through C) Hematoxylin/eosin staining of paraffin-embedded section (original magnification × 400). (D) Toluidine blue staining of Epoxy resin-embedded sections (original magnification × 1,000).