Scanning electron micrograph of woven dacron graft material, used to replace natural body tissues. Most Dacron grafts are in the shape of a tube to replace or repair blood vessels. A Dacron graft can be used as a stent to repair an artery, blood vessel, or other hollow structure in your body (such as the tube that carries urine) to hold it open. Supplied by David Gregory & Debbie Marshall, courtesy of Wellcome Images.