Effects of Ca supplementation for 4 months on the accumulation of plaques and minerals in aortas. Panels A–D show typical examples of the effects of calcium supplementation on accumulation of lesions and calcification in a sibling group. The rationale for the selection of the middle and proximal sections, respectively, for lesion accumulation and calcification was given in detail in the Experimental Procedures section. The cross sections of the middle section of aortas from sibling brothers were stained with H&E (Panels A and B) to show intimal thickening (lesions). The cross sections of the proximal section were stained with AR (Panels C and D) to show mineralization (arrows). A & C are cross sections obtained from rabbits fed the atherogenic diet with normal levels of dietary Ca. B and D are cross sections from rabbits with Ca supplementation. The thickened intima to media ratio was used to semi-quantify the extent of lesion accumulation as described in "Experimental Procedures" section. Likewise, the extent of calcification was expressed as the ratio of calcified area to the area of thickened intima. Intima/media ratios: A, 0.77 vs. B, 0.32. Calcified area/intima ratio: C, 0.47 vs. D, 0.00. Panel E provides the paired Student's t-test for the significance of the differences in the ratios between the two respective groups each with 16 siblings.