Chemical composition of the rabbit aorta during development.

Changes in both the relative and the absolute amounts of collagen and elastin in segments of the aortic wall of New Zealand white rabbits (1-130 weeks old) were determined by chemical analysis. As in other mammals, elastin was the major component of the wall of the thoracic aorta although the proportion of collagen increased along the abdominal aorta and into the more distant arteries. Data on the absolute amounts of collagen and elastin per aorta showed that collagen and elastin deposition was most rapid during the early postnatal weeks. Although this deposition slowed in later weeks, it continued in both segments of the aorta throughout the period of this study. The proportion of the wall mass attributable to collagen and to elastin increased very rapidly during the first postnatal weeks and then, after 20 weeks, declined. The results of the present study indicate that there is a significant increase in some unidentified nonscleroprotein component within the aortic wall of older rabbits.