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Figure 1 (A) A decalcified histologic section of an aortic valve stained with hematoxylin-eosin. Eosin-stained dystrophic bone is seen between the endothelial lining of the valve and the calcium nodule in the lower part of the image. A cement line joins the ossification to the calcium nodule. Dystrophic bone is marked with an arrow. Scale bar = 100 µm. (B) Intense tenascin-C (TN-C) immunostaining (arrows) can be seen in the vicinity of the calcified areas (marked with an asterisk) of the stenotic valve. Notice the inflammatory cells and the neovascularization (arrowheads) in the right corner of the field. (C) TN-C immunoreactivity can be seen as a basement membrane-associated zone in undiseased valves (arrow). The valvular stroma is otherwise negative. (D) Around the areas of calcification (asterisk) in a stenotic valve, intense TN-C immunopositivity (arrows) can be seen. Linear basement membrane-associated staining is missing. (E) Immunostaining with an antibody to alpha-smooth muscle actin. Strong positivity for this antigen can be seen in stromal fibroblast-type cells, suggesting myofibroblastic differentiation of the cells. (F) In situ hybridization of a stenotic valve. Strong signals for tenascin (arrows) can be seen in fusiform fibroblast-like cells in the stroma.