Histology of the aortic valve of adenine-fed and control rats. Histology of the aortic valve of adenine-fed group 1 and control group 2 rats, at weeks 9 and week 21. Arrows indicate valvular calcifications that are mainly situated in the aortic annulus. After cessation of the adenine-diet in group 1 (after week 9), regression of calcifications is observed. Scale bar is 500 μm, original magnification at 25 x, haematoxylin-eosin staining.