Figure 5.

Neutrophilic and histiocytic infiltrates were identified in the lungs, spleen, and liver of F344 rats on day 3 after exposure to 10³ CFUs Francisella tularensis, strain SCHU S4. Inflammatory cell infiltrates (arrows) consisting of neutrophils and histiocytes were identified in the lungs (A and B), spleen (C and D), and liver (E and F) of F344 rats euthanized 3 days after challenge. In the lungs, inflammation was localized primarily to the conducting airways and centriacinar alveoli and, to a lesser extent, the vascular adventitia. In the spleen, the inflammation was randomly distributed as discreet foci in the red pulp. In the liver, the inflammation was randomly distributed as discreet foci within the hepatic parenchyma. Hematoxylin and eosin stain was used. Scale bars: 500 μm (A); 20 μm (B, D, and F); 200 μm (C and E).