Figure 2.

Kidneys from Stx2-challenged animals show interstitial hemorrhage, inflammation, and mesangiolysis. Light microscopic images shown represent the most severe changes seen at each dose; features described were seen in a subset of low-dose specimens and all high-dose specimens. Stx2 dose indicated at left for each row. Scale bars (for each column): 50 μm (D); 100 μm (E); 0.5 mm (F). A and D: PAS-stained kidney cortex. Glomeruli show mild mesangial expansion and widespread mesangial cell pyknosis and karyorrhexis (arrows). There is also segmental thickening of glomerular capillary walls, and focal inflammatory cell margination. B and E: H&E-stained kidney cortex show features of focal acute tubular injury, focal interstitial hemorrhage, and focal interstitial inflammation with many eosinophils, more prominent at higher doses of Stx2. Focal protein reabsorption is also present in tubular epithelia. C and F: H&E-stained kidney tissue. Renal medullary columns show extensive interstitial hemorrhage. Vasculature showed no significant pathologic changes.