Artery wall. Coloured scanning electron micrograph (SEM) of a close-up of a resin cast of a large artery. The cast was made by injecting resin into the artery, followed by chemical digestion of the surrounding tissues. This means that the surface of the resin cast shows the pattern seen on the inside of the artery. This is formed by the inner layer of the artery, the endothelial cells of the tunica intima. Arteries are blood vessels that carry blood from the heart to the body tissues. Except for the pulmonary artery, the arteries carry oxygenated blood.