[Quantitative morphology of the coronary arteries in the second and third decades of life (author's transl)].

1. In 8 cases in the second decade and 10 cases in the third decade without coronary sclerosis and 5 cases with early sclerosis quantitative measurements were made on graded sections of the coronary arteries which were fixed in toto by compression. The surfaces of the lumen, intima and media were determined planimetrically and the thickness of the intima and media and the radius of the lumen of the three main branches of the coronary arteries were determined micrometrically. A post-mortem coronary angiogram was made of each heart and the connective tissue content of the right and left heart was determined planimetrically. 2. Higher values are found in the absolute measurements of surface and thickness of each cross-section in the third decade than in the second. In both age groups the anterior descending ramus is predominant in all criteria. About the end of the second decade the intima attains the thickness of the media and shows the greatest variability of all parameters, especially in the second decade. In both decades the media plays an equally important role in growth as the intima. In the anterior descending ramus the intima has a higher percentage growth rate than in the right coronary artery and in the left ramus circumflexus. In the third decade it has reached a mean thickness of 122 mu in the initial part of the anterior descending ramus and a mean surface area of 1.18 mm2. In the same area the mean thickness of the media also in the third decade, would be 124 mu, and the mean surface area of the media 1.64 mm2. 3. The indices of coronary sclerosis and coronary insufficiency were determined by the method of Freudenberg, Knieriem, Möller and Janzen (1974). Using the mean values for the second and third decades and calculating the regression in the fourth to seventh decades, we found as upper normal limits a coronary sclerosis index of I = 0.3 for hearts without coronary sclerosis, for the coronary sclerosis index II = 0.6, for the coronary insufficiency index I = 0.3, for the coronary insufficiency index II = 0.6 and for the coronary insufficiency index III = 1.0.