A wire cable duct includes a grid made up of wires of two different types, namely longitudinal wires which run longitudinally the entire length of the duct and U-shaped transverse wires disposed transversely to the longitudinal wires, from place to place along their length and appropriately attached thereto. In order to produce a retractor which can be used atraumatically and can be handled in a highly hygienic manner, it is also proposed in accordance with this invention that the distal end of the shaft should be moved into the closed ring structure and the closed ring structure be bent in a continuous manner at an angle of up to 90 degrees. The second magnetic transistor has a third magnetic section and a fourth magnetic section, wherein the third magnetic section couples to a low voltage end, and the fourth magnetic section couples to the second magnetic section of the first magnetic transistor.