APOE and atherosclerosis: These findings indicate that in Apoe-/- mice fed a normal chow diet, the progression of atherosclerosis towards late disease stages is coincident with the transition of atherosclerotic lesions of the aortic valve from a more cellular macrophage-rich and less necrotic phenotype at 26 weeks of age to a less cellular and more necrotic phenotype at 52 weeks of age (Figure 2a–c and Figure 3a–d).