A flexible wire loop made from a single wire is bent through 180 deg on itself at its distal and proximal ends (1a) to form a regular loop in its center part so the incoming sectors of the wire are fixed in a distal end tube (2) and in the proximal end tube or sleeve (5). A control wire (6) moves axially freely in the sleeve (5). The wire is free in the tube (2) and the sleeve (5) in its parts immediately preceding the fixed ends. Loop and control wire (1 and 6) enter the sleeve from opposite ends, the loop wire pulled in and run out by means of the axial movement of the control wire (6). The control wire forms a continuation of the proximal end of the loop wire (1). An endoscopic instrument using this loop principle has four wires forming a four-wire basket or cage.
