The elasticity of the internal lamina

The elasticity has been investigated post mortem of the external iliac artery from 48 cases, matched normotensives and hypertensives, males and females, from the 3rd to the 8th decades. The lamina is shown to be truly elastic in that it resists stretch, for there is no increase in the length of the lamina, measured histometrically, in arterial cross-sections when segments of the artery are distended by pressures equivalent to the lifetime systolic blood pressure, or indeed much higher pressures even to the point of rupture. In this process gaps in the lamina, the representation on histological slides of fenestrae, become wider than in the undistended state. With advancing age there is a very slight increase in the length of the lamina but this is not accompanied by any increase in the number of gaps except in the case of male normotensives over the age of 60 yr. Between the 3rd and 8th decades gaps do not increase in size in the laminae of arteries from normotensives. The gaps do show an increase in size in hypertensives but only those above the age of 60 yr.