[The number of nuclei and the thickness of the media and intima of the coronary arteries of normal hearts in the second and third decades of life and in hearts with coronary sclerosis and hypertension].

The number of nuclei in the cells of smooth muscle of the media, and the thickness of the media and intima of coronary arteries were investigated by histometric measurements with regard to their behaviour in different stages of life In normal hearts and in hearts altered by disease. Seven normal hearts in the second decade of life, 7 normal hearts in the third decade, 5 hearts with coronary sclerosis (average age 33 years) and 5 hearts with hypertension (average age 47 years) had been examined. After fixing the coronary arteries under a pressure of 110-130 nm Hg and postmortem coronary angiography, the anterior descending and circumflex rami of the left coronary artery and the right coronary artery were cut into blocks of tissue 1 cm long from which frozen sections were made after embedding in gelatine and HE staining. The number of cell nuclei and the thickness of the media and intima were determined micrometrically along 8 radii of each cross-section. From the quantitative findings for the 3 arterial branches in the individual case, a mean value was obtained for each parameter, and from these, a mean value for each group. In normal hearts and in coronary scelrosis, the number of cell nuclei decreases steadily towards the periphery of the cross-sections. In hypertension, in which the highest numbers of cell nuclei are found, hyperplasia of the cell nuclei right into the periphery is marked. The mean number of nuclei/100 mu thickness of media remains the same in all cross-sections of normal and pathological hearts alike. The average number of nuclei in the first 4 cross-sections of the three arterial branches increases from the second to the third decade, through the casses with coronary sclerosis to the cases with hypertension in the proportions 5.6 : 6.7 : 10.7 : 11.7. The difference between the third decade and coronary sclerosis decreases from the first 4 cross-sections to half, while between the coronary sclerosis and hypertension it increases. Hypertrophy and atrophy of the muscle fibres are not taken into account in these measurements. The thickness of the media in the groups behaves like the number of nuclei: in hypertension with the highest values, there is no significant decrease as far as the 8th cross-section, while in the coronary sclerosis and third decade groups the values come closer together after the 6th cross-section. The difference in the middle and peripheral vascular sections are more distinct than in the proximal sections for coronary sclerosis and hypertension. The thickness of the media increases from the second decade to the hypertensive group in the first 4 cross-sections from 70 mu through 106 mu and 131 mu up to 167 mu. The thickness of the intima increases distinctly more rapidly in comparison to the media from 52 mu through 95 mu, 203 mu to 279 mu in hypertension. The media of the coronary arteries in coronary sclerosis and to a greater extent in hypertension, undergo an increase in functional material through hypertrophy and hyperplasia.