Some particular aspects of the microarchitecture of human coronary arteries.

The following light-microscopic features characterize the microarchitecture of human coronary arteries compared with other organ arteries of muscular type and similar size: (a) the rapid development of a diffuse thickened intima which in adolescents becomes the main layer of the coronary artery wall; (b) the slow post-natal increase in the number of circularly oriented rows of smooth muscle cells of the media; (c) the occurrence of numerous longitudinal muscle columns, particularly in arterial segments and branches which run from the base to the apex of the heart; (d) the complex organization of branching points, including the presence of large pads or cushions, a very thick intima and many longitudinal muscle columns, some of which exhibit a spiral course at the level of the branch mouths with the formation of muscle rings round the entrance orifices.