A catheter introducer system for endoscopy includes a steering section and a propulsion section located near the end of the catheter that is introduced in a body cavity. The propulsion section is designed to pull the rest of the catheter inside the body cavity, so there is no need to push the catheter along. The propulsion section includes a distal and proximal gripper portion, each of which includes a suction ring extending circumferentially around the catheter. Each suction ring can include a plurality of suction holes disposed either on a recessed portion of the suction ring or on a portion surrounded by a peripheral ridge extending above the outer surface of the suction ring. The suction ring can also include an inflatable member for urging tissue against the perimeter of the suction holes.