Histological analysis of lungs from BALB/c mice inoculated with wild-type Y. pseudotuberculosis. Mice were inoculated with 300 to 500 CFU of Y. pseudotuberculosis, and lungs were harvested 1 (A and F), 2 (B and G), 4 (C and H), 6 (D and I), and 7 (E and J) days postinoculation, sectioned, and stained with hematoxylin and eosin. Slides are shown at a magnification of ×10 (A to E) or ×60 (F to J).