The applicator for utilization in combination with an endoscope tube comprises a coil connected to a longitudinal passage through a shaft and comprising hollow turns connected to the shaft passage for reception of a sewing thread, whose proximal extremity is passed through a loop projecting from a radial opening at the distal extremity of the shaft, is then drawn through the shaft passage and fastened to the proximal shaft extremity. Tying the single stitch after piercing the tissues is performed by passing the needle axially through the coil and then around the thread and twisting the coil out of the loop formed thereby to form the first half of a knot which is then complemented by the second half of the knot tied in the same way, the knot being tied by subsequently pulling together the two halves.