Saphenous vein. Light micrograph of a section through the wall of a healthy human saphenous vein. This is one of the two veins that carry blood up each leg from the foot. The wall of the vein contains many muscle fibres (purple) arranged in concentric layers around the vein's central cavity (lumen, white, lower frame). Local movements of these muscle fibres, along with the action of valves, prevent blood from flowing backwards down the vein under the effects of gravity. Magnification unknown.