FIG. 2.
Histological characteristics of IL-10−/− mice challenged with M. avium subsp. paratuberculosis. At 14 weeks postchallenge, histopathological sections of colons from IL-10−/− mice that received a single dose of 200 μl of control vehicle (cream only), 104 CFU of live M. avium subsp. paratuberculosis (live MAP) in cream, or 104 CFU of heat-killed M. avium subsp. paratuberculosis (heat-killed MAP) in cream by gavage and were maintained under otherwise germfree conditions were fixed, sectioned at 6 μm, and stained with hematoxylin and eosin. Mild (open triangles) and heavy (solid triangles) cellular infiltrates were noted in the groups (i.e., live M. avium subsp. paratuberculosis ≫ heat-killed M. avium subsp. paratuberculosis > controls). For live M. avium subsp. paratuberculosis-challenged mice, aggregates of cellular infiltrates were typically associated with focal lesions, or hypertrophied epithelial cells with reduced crypt lengths. Sections were examined by light microscopy (magnification, ×40). Experimental groups consisted of 15 mice each. Representative samples are shown.