Figure 1: Heterotopic ossification in dysfunctional aortic valves. (a) Rimlike ossification (arrows) in calcified atheroma, accompanied by thick-walled arteriole-like neovessel (arrowhead), and a high-power view (inset) of ossification stained red by EVG and nearby thin-walled capillary-like vessels (asterisks). (b) Heterotopic ossification (arrows) and aggregated thin-walled vessels (arrowheads) in a nodular calcific tricuspid aortic valve without thickwalled vessels, and a high-power view (inset) showing bone and nearby thinwalled vessels (asterisks). (c) Enchondral ossification composed of bone and fatty marrow adjacent to metaplastic cartilage accompanied by thin-walled vessel proliferation (arrowheads). (d) Focal and minute ossification (arrow) in calcified lesions without nearby neovessels and a high-power view (inset) of thin rim-like bone stained red by EVG adjacent to edematous stroma without vessels.