A new method for quantitating the medial component of pulmonary arteries: Factors affecting the measurements

Current methods for quantitating the media of pulmonary arteries are inadequate in that either they produce measurements of the media and artery size that are affected by vasoconstriction, or they are complicated to use. We developed a method that overcomes these problems. It produces measurements of medial area and the artery size is expressed in terms of the total length of the internal elastic lamina. The measurements are obtained directly from histologic sections using a light microscope with a camera lucida attachment in conjunction with a microcomputer linked to a digitizing board. Repeatability of the measurements is excellent but it is essential to digitize at a magnification at which crinkles in the internal elastic lamina are clearly visible. Arteries that are considered to be digitizable are representative of the total muscular pulmonary artery population.