The static elastic properties of carotid arteries from fetal sheep

摘要: Simultaneous measurements of volume, pressure, and length were made on 91 cylindrical segments of isolated carotid arteries from 61 fetal sheep of 85 to 141 days gestation (term = 147 days). Tension–length curves were calculated from these data by utilizing the Law of Laplace (tension = pressure × radius). Analysis of the curves suggests that the elastance (tension/strain) increased exponentially with age in all regions of the curve (i.e. for elastin, collagen, and in the physiological range). The unstretched radius, the wall thickness of non-distended sections of the arteries, and the interconnections or 'links' between collagen fibers all appeared to increase linearly with age. Histological sections indicate that these arteries develop an external elastic membrane between 85 and 92 days of gestation. With maturation, the medial elastic lamellae become less organized owing to ingrowth of collagen and muscle. Weight may be more important than age in assessing maturity since arteries from twins of different weights behaved quite differently. The mathematical problems encountered in assessing geometrical relationships over restricted regions of curves are discussed in detail.