Histogenetic differences between parent and daughter vessels of human coronary arteries.

The age-dependent changes of the parent vessels of human coronary arteries are characterized by a very early appearance and very intense development, as well as by a rapid association of degenerative processes. In contrast, the age-dependent changes of the daughter vessels of human coronary arteries are characterized by a very late occurrence and very slow development, as well as by the lack of associated degenerative processes. This histogenetic difference between parent and daughter vessels was not observed in other organ arteries. The two different histogenetic areas of the coronary tree appeared separated by a boundary constantly found at the level of the branching area, in a point where longitudinal muscle columns of the parent vessel criss-cross proximate to the branch orifice and describe half a spiral round it. No particular wall changes were observed when an epicardial branch became an intramyocardial one.