ANALYSIS OF THE STRAIN AND STRESS-DISTRIBUTION IN THE WALL OF THE DEVELOPING AND MATURE RAT AORTA

The variation of wall stress distribution with age in the thoracic and abdominal aortas of normotensive rats was studied, Dimensions of the zero-stress configurations were measured at the ages of 4, 8, 12, 20, and 52 weeks, Using data from previously published inflation tests, th e circumferential stress-strain relationship was obtained in each age group, The calculated stress distribution showed that the average circ umferential stress remained practically constant after the age of 20 w eeks, The circumferential stress at the innermost part of the arterial wall was greater than the stress at the outermost part, but the diffe rence was maintained at a moderate level with adjustments in the zero- stress configuration, It is speculated that, after the age of 20 weeks , changes in arterial geometry and theological properties tend to main tain a constant stress distribution under varying conditions of loadin g, This distribution was achieved by enhanced growth at the inner part of the media in comparison with the growth at its outer margins and s uggests that during development and maturity, the growth of the aorta is modulated by circumferential stress.