FIG 5.

Pathology of spleens infected with F. tularensis Schu S4, the F. tularensis waaY mutant, and the F. tularensis waaL mutant. Sections of spleens are shown for mice infected with Schu S4 for 3 and 5 days (a and b) or with F. tularensis mutant strains for 3, 6, and 12 days (c to f). The lesions observed in samples from F. tularensis waaY and F. tularensis waaL mutant infections were indistinguishable from one another. (a) Spleen section from F. tularensis Schu S4-infected mouse at 3 days postinfection. (b) Spleen section from F. tularensis Schu S4-infected mouse at 5 days postinfection. The white asterisks denote areas of diffuse to coalescing necrosis in the red pulp. (c and d) Spleen sections from F. tularensis mutant-infected mouse at 3 days postinfection (c) and 6 days postinfection (d). The spleen had increased neutrophils (arrows) in the red pulp. (e) Spleen section from F. tularensis mutant-infected mouse at 6 days postinfection. The spleen had rare thrombi in red pulp (black asterisk) and lacked detectable necrosis. (f) Tissue section from F. tularensis mutant-infected mouse at 12 days postinfection. The spleen had white pulp with large germinal centers (white asterisk) and red pulp with granulocytic/myeloid-predominant extramedullary hematopoiesis (arrows). The scale bar applies to each panel shown.