FIG. 2.

MyD88^−/− mice infected with M. tuberculosis exhibit more bacilli, exacerbated pathology, and reduced NOS2 expression in lungs, as well as delayed granuloma formation in liver. Formalin-fixed, paraffin-embedded lung (A to D, G, and H) and liver (E and F) tissue sections from mice 3 weeks after infection with aerosol M. tuberculosis were stained by the Kinyoun acid-fast method to detect mycobacteria (red staining) (A and B) or with hematoxylin and eosin stain (C to F). Note the absence of granulomas in panel F. NOS2 was visualized immunohistochemically in serial sections of these same tissues (G and H). Sections shown are representative of multiple fields from the organs of at least three animals per group. Original magnifications are ×63 (A and B), ×5 (C and D), ×10 (E and F), and ×20 (G and H).