“…Such a depression might, at critical stages of aortic growth and associated reniodeling, underlie aneurysms and ruptures. This opinion has since been supported by several sulisequent studies rn e~ivol-'Jti and in nitro 31 In the present paper, further evidence for or against this view has been sought by a combined histological, histocheinical, quantitative chemical, and EM study of the elastin and collagen contents. relative to age and body weight, in normal mice, in ztfcro and up to 30 da!…”