A medical system including a grasp device having a longitudinal portion and an end effector attached to the longitudinal portion； an overtube having a collection lumen and a water supply lumen through which the longitudinal portion is inserted and having a distal end opening positioned inside the collection lumen； and an aspirator connected with the collection lumen, wherein the end effector further has a first member； and a second member mounted so as to open and close the end effector by moving relatively to the first member, wherein the second member forms an interior space between the first member and the second member for accommodating the tissues and has an opening communicating with the interior space when the end effector is closed, and the proximal end portion of the second member is enterable into the collection lumen.
