of the present invention that the sharply pointed ends of the fastener's head be formed in such a way, and presented to the tissue in such a way, that they will be able to engage the tissue and anchor the fastener in the manner just described. Thus, the fasteners have their pointed ends formed by terminating the ends of the head with a single planar surface 25 (or 30) set at an acute angle relative to the longitudinal axis of the head, whereby the two points are directed away from one another. In this preferred embodiment, bevelled end surfaces are arranged so that one of the points is positioned on the "filament" side of the head and the second point is positioned on the "outside" side of thelongitudinal axis of sheath 406, so that the sheath is effectively sharply pointed at its front end. Rear surface 421 is disposed at an angle substantially perpendicular to the longitudinal axis of sheath 406. Sheath 406 has an axial bore 426 extending between its front surface 416 and its rear surface 421, and a straight slot 431 extending rearwardly from the sheath's front surface 416. Slot 431 terminates in a rear edge surface 436. Sheath 406 also includes a rigid finger grip 441 which extends radially outward from the sheath near its rear surface 421, and a stop 446 which extends radially outward from the sheath near its front end surface 416. Plunger 411 includes a body section 451 and a head section 456. Body section 451 and