Embryonic development of coronary vasculature in rats: Corrosion casting studies

Abstract

The aim of this study was to analyze the development of coronary vessels at different stages of embryonic life in rats using corrosion casts and scanning electron microscopy (SEM). We studied morphologic details of vessel maturation, expansion, and pattern formation from the stage of development when the coronary system forms patent connections with the aorta and the right atrium (embryonic day 16 (ED16)) to full-term fetus (ED21). The internal surface morphologies of the arterial and venous vessel walls were different and were dependent on the distance from the orifice and the capillary system. They also depended on the maturation state of a given vessel. In various branches of the coronary system we demonstrated round, fusiform or polygonal, endothelial cell imprints. The capillary network was dense, however, at the early stages of development, it formed a thin layer over the myocardium. By ED21 capillaries assumed an orientation parallel to the long axes of the cardiac myocytes. During all stages of development, different forms of angiogenesis by intussusceptive growth were observed. Splitting of the vessel wall occurred in two or three points along the vessel, forming two-or three-link chains. Certain areas of vessels resembled doughnuts, from which several sister vessels originated. The coronary arteries were situated deep within the myocardial wall. The major coronary veins were mostly located on the surface of the capillary plexuses of the myocardial wall. In conclusion, this method of vessel casting enables the detection of angiogenesis by intussusceptive growth, and the visualization of a capillary's position to the myocardial wall, thickness of the capillary plexuses, and the internal surface morphology of major vessels. Anat Rec Part A 270A: 109 -116, 2003.

Novel tool to suppress cell proliferation in vivo demonstrates that myocardial and coronary vascular growth represent distinct developmental programs

“…] dium dependent on coronary perfusion. Consistent with this, corrosion studies of rat hearts revealed that the major coronary vessels do not become patent with the aorta until E14.5 (Ratajska et al, 2003). Thus, during initiation of vascular development, myocardial proliferation is genetically independent of vascular growth.…”

Fibroblast growth factor signals regulate a wave of Hedgehog activation that is essential for coronary vascular development

“…Corrosion casting of developing coronary vessels in the rat demonstrated that veins grow within the subepicardial space while arteries grow within the myocardial wall (Ratajska et al 2003). Given this, it is interesting to consider the possibility that subepicardial and intramyocardial blood vessels represent or give rise to veins and arteries, respectively.…”

Embryonic development of the proepicardium and coronary vessels

“…An increase in shear stress within the arterial side of the coronary system and rapid blood flow in arterial wall explains why the vascular wall of arterial system differentiates earlier than the cardiac veins (Vrancken Peeters et al, 1997a). In addition, the specific shape of the internal wall of coronary vasculature of the embryonic heart can be explained by the elevated speed of blood flow within the arteries as compared to veins (Ratajska et al, 2003). The development of the coronary vessel is not restricted to the embryonic period of life and it continues postnatally.…”