Mechanical and Chemical Regulation of Arterial and Venous Specification - Mechanical and Chemical Signaling in Angiogenesis - page 4

Fig. 2 Distinctive anatomical structure of artery and vein. Each vessel consists of connective
tissue (tunica externa), smooth muscle (tunica media), elastic tissue and endothelium (tunica
interna) layers. Artery exhibits thicker smooth muscle layer (tunica media)
2.2 The Effects of Hemodynamic Forces on Anatomical
Structure of Vasculature
Blood vessels are formed by layer(s) of endothelial cells with elastic tissues and
perivascular smooth muscle cells (Fig. 2 ). Arteries are supported by thick elastic
smooth muscle layers so that they can withstand higher pressure. In contrast, veins
contain thinner elastic smooth muscle layers with semilunar valves that prevent
blood backflow. Therefore, arteries and veins adapt to differential hemodynamic
forces that they are respectively exposed to.
2.3 The Effects of Hemodynamic Forces on Vascular
Development
It has been reported that blood flow cast major impacts on vascular network
remodeling and vascular gene expression. However, its role in specification and/or
maintenance of arteries and veins remains ill-defined.
In one study, no-flow mouse embryos were generated by snipping the inlets to the
heart at both sides of the heart of 3- to 4-somite stage embryos [ 10 ]. In these no-flow
embryos, as compared to normal embryos, no significant differences in the expression