A, Representative gross appearance of abdominal aortas of AngII-treated Col+/+/apoE−/− (left) or ColR/R/apoE−/− (right) mice. B, Representative Hematoxylin-Eosin staining of the abdominal aortas from Col+/+/apoE−/− (left) and ColR/R/apoE−/− (right) mice. The aortic wall protrudes and extends to the right in the ColR/R/apoE−/− mouse. C, Quantitative analysis of circumference of the internal lamina. ColR/R/apoE−/− mice (n=8) had greater abdominal aortas compared with Col+/+/apoE−/− (n=6) or Col+/+/apoE−/− mice (n=8). Bars and error bars represent means and S.E.M, respectively. D, Collagenase resistance also increased the incidence of AAA formation (>1.5-fold increase in diameter).