Radial compression mechanism includes a base member and a plurality of elongated compression dies. The dies are arranged in a generally circular orientation on the base member with a contact surface of each die in sliding contact with a base surface of an adjacent die. A portion of each base surface of each die cooperates with portions of base surfaces of adjacent dies to define a generally cylindrical central cavity moved between open and closed positions by a driving mechanism. The dies are cammingly coupled to the base member and to the driving mechanism so that rotation of the driving mechanism about the central axis causes each die to move generally arcuately about a point of camming engagement with the base member.