Atherosclerotic lesions in aortas. (a and b) Sudan III–stained, longitudinally opened aortas from apoE-KO (a) and apoE-KO/eNOS-Tg mice (b) at the age of 16 weeks. (c) Quantitative analysis of atherosclerotic lesion size in 16-week-old mice. After 12 weeks on a high-cholesterol diet, the lesion size in apoE-KO/eNOS-Tg mice was significantly greater than that in apoE-KO mice. Percentage of lesion area is the lesion area per total area of aorta. *P < 0.0001 vs. apoE-KO males; **P < 0.001 vs. apoE-KO females.