A graft delivery system (100), comprising: a graft cover retractor (110) including: a grooved hollow worm (130) including an outer surface, and threads extending from the outer surface； a graft cover advance hollow nut (242) having: a first inner surface； a second inner surface distal to the first inner surface； a proximal end edge surface (703) positioned between the first inner surface and the second inner surface； and threads (704) extending from the second inner surface, in which the grooved hollow worm (130) is mounted within the graft cover feed hollow nut (242) such that the threads of the screw without Grooved Hollow End (130) engage threads (704) of the Graft Cover Lead Hollow Nut (242)； and a graft cover spacer anchor (252) having: a distal end configured to removably fit within a proximal end of the graft cover advance hollow nut (242) between the threads of the hollow worm screw grooved (130) and the first inner surface of the graft cover feed hollow nut (242)； and attached to a graft cover (105), wherein when the distal end of the graft cover spacer anchor (252) is within the proximal end of the graft cover advance hollow nut (242) and is in contact with the proximal end edge surface (703) of the graft cover feed hollow nut (242), and the graft cover feed hollow nut (242) is rotated about the grooved hollow worm screw (130 ) in a first direction of rotation, the graft cover (105) retracts； and when the distal end of the graft cover spacer anchor (252) is within the proximal end of the graft cover advance hollow nut (242) and the graft cover spacer anchor (252) slides in proximal longitudinally along the slotted hollow worm (130), the distal end of the graft cover spacer anchor (252) is withdrawn from within the proximal end of the graft cover advance hollow nut (242), and the graft cover (105) is also retracted by sliding.Un sistema de administración de injertos (100), que comprende: un retractor de cubierta de injerto (110) que incluye: un tornillo sin
