Redistribution of iron from splenic and hepatic macrophages to hepatocytes and renal proximal tubule cells in HO-1^−/− mice. (A) Perls Prussian blue staining of paraffin-embedded tissue sections revealed pronounced high iron levels in splenic macrophages of the WT, compared with almost undetectable macrophage iron in the HO-1^−/− animals, whereas very little iron was detected in renal proximal tubules of the WT, but iron levels were greatly increased in the renal proximal tubules of HO-1^−/− mice. Slices of paraffin-embedded tissue from 2 mice (5 and 12 months old) for both WT and HO-1^−/− are shown. (B) Redistribution of iron in liver from Kupffer cells (arrowheads), which were absent in HO-1^−/− mice, to hepatocytes (arrows). (Inset) A 2.5-fold digital magnification of an area from the adjacent field, to better demonstrate the different morphologies of iron-containing cells in WT versus HO-1^−/− animals.