Changes in gross and histopathology caused by C. jejuni strains during serial passage (experiment 2). C57BL/6 IL-10-/- mice develop typhlocolitis with either "watery" contents (primary challenge) or "bloody" contents (after adaptation) following oral inoculation with C. jejuni. Panels A-D show images of gross pathology; panels E-H show images of histopathology from the same mice. Panel A shows thickened cecal and colon section with watery contents in a C. jejuni infected mouse 30 days after a primary challenge with strain 11168. Panels B and D show thickened cecal and colon section with bloody contents from a C. jejuni infected mouse 30 days after challenge with adapted strain 11168. Arrow indicates greatly enlarged ileocecocolic lymph node and arrowheads point to cecal tip with dark contents. In D cecal tip is opened to expose the frank blood (arrowheads). Panel C shows the cecum and colon of a normal sham inoculated control mouse. Panels E-H show histopathology from the same mice (E-G images taken at 10× magnification, H image taken at 40× magnification). Panel E shows mucosa of colon from the C. jejuni infected mouse with watery colon contents of Panel A. Note hyperplasia, intense mononuclear cell infiltration (white arrows) and slight neutrophilic exudates. Black arrows indicate the presence of intact epithelium. Panel F shows mucosa of colon from C. jejuni infected mouse with bloody colon contents from Panels B and D. This section also has intense cellular infiltrates, but it also has loss of epithelial layer (arrows) and blood and neutrophils present in exudates (arrowheads). Panel H shows a close-up of area in Panel F indicated with arrows. Long arrows point to sloughed villus tip epithelium. Arrowheads point to exudates with visible red blood cells and neutrophils. Panel G shows the colon mucosa of a normal sham inoculated control mouse for comparison.