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Figure 2 (A) Typical examples of immunohistochemistry for endothelial cell markers including von Willebrand factor, CD31 and eNOS in atrial appendages from noncardiac (N) and cardiac patients (HD), between which the immunoreactivity for vWF in the endocardium differed greatly. No specific staining was seen in control sections incubated with nonimmunized immunoglobulin (C). Bar = 100 µm. (B) Electron micrographs of left atrial appendage of a cardiac patient, which had been stained with the immunogold method using polyclonal anti-vWF antibody. Gold particles (arrows) are present in vesicles within the endocardial endothelium and in the subendothelium. EC = endothelial cell; L = lumen. Original magnification x12,000.