FIG 4.

Pathology of lung tissue 6 days after inhalation of spores. Samples were fixed in 10% neutral buffered formalin, processed to paraffin wax, sectioned to 3 to 5 μm, stained with hematoxylin and eosin, and examined by light microscopy. Slides were randomized by a third party before microscopic examination to avoid prior knowledge of group or treatment. (A) Images from animals receiving only PBS vehicle. The region shows iatrogenic thickening of the alveolar walls due to the collapsed nature of the tissue. Arrows indicate bacilli located in alveolar spaces. Ve, vessel lumina. (B) Images from a region of inflated lung from animals receiving 10 mg/kg rEnvD over 5 days.