Figure 6.

Inflammation in the lungs, spleen, and liver increased in severity and became more necrotizing over time after exposure to 10³ CFUs Francisella tularensis, strain SCHU S4. Inflammation (arrows) in the lungs (A and B), spleen (C and D), and liver (E and F) of a rat euthanized on day 7 after exposure involved more tissue than on day 3 and consisted primarily of histiocytes with fibrin and necrotic cell debris and fewer viable neutrophils. Inflammation in the splenic red pulp coalesced and effaced most of the red pulp and encroached on the white pulp, which was reduced in volume (arrowheads). Hematoxylin and eosin stain was used. Scale bars: 500 μm (A); 20 μm (B, D, and F); 200 μm (C and E).