Blood vessel between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart. The word "vascular", meaning relating to the blood vessels, is derived from the Latin "vas", meaning vessel. A few structures (such as cartilage and the lens of the eye) do not contain blood vessels and are labeled. The arteries and veins have three layers. The middle layer is thicker in the arteries than it is in the veins: Capillaries consist of little more than a layer of endothelium and occasional connective tissue. When blood vessels connect to form a region of
Transposition of the great vessels which vessels are involved. Although "transposed" literally means "swapped", many types of TGV involve vessels that are in abnormal positions, while not actually being swapped with each other. The terms TGV and TGA are most commonly used in reference to dextro-TGA – in which the arteries "are" in swapped positions; however, both terms are also commonly used, though to a slightly lesser extent, in reference to levo-TGA – in which both the arteries and the ventricles are swapped; while other defects in this category are almost never referred to by either of these terms. In dextro-Transposition of the great arteries