IHC reveals release of XO from liver and presence of XO on liver vascular endothelium of sph/sph mice. (A) DAB-based IHC of liver sections from normal (+/+) and sph/sph mice with an antibody that detects both XD(the form stored in liver hepatocytes) and XO (generated by cleavage of XD by plasma proteases). Pictures shown are representative of results obtained from 3 different mice of each genotype (+/+, sph/sph; all mice more than 12 weeks old). Diffuse staining is seen in hepatocytes from normal mice (botom left panel). Sections from sph/sph mice (bottom right panel) show the presence of hepatocytes with little or no staining for XD/XO (). Bar, 10 μm. (B) High magnification of liver sections from normal and sph/sph mice. Top panels, staining for XD/XO, with presence of XO staining on endothelium of blood vessel in sph/sph (▶) but not +/+ mice. Bottom panels: adjacent sections stained (▷) with an antibody to VWF, an endothelial-specific marker. Bar, 10 μm. Pictures shown are representative of results obtained from 3 different mice of each genotype as described for Figure 5A.