A manually-operable surgical tool, suitable for laparoscopic operations, has separable parts which cooperate to move a pair of end effector elements which can be readily replaced by another pair of end effector elements. A handle portion enables controlled longitudinal movement of an elongate inner element relative to an outer surrounding tubular element. The tubular element has a distal end with a first cleft and a pair of parallel cantilevered inwardly-oriented opposed cam pins. The distal end of the elongate inner element is provided with a second cleft and a transverse force-application pin. The selected end effector elements rotatably fit inside the cleft of the inner element to receive an applied force via the force-application pin. Each end effector element has a blind-ended cutout having an open end for engaging at least with a corresponding one of the cam pins. As the inner element moves longitudinally of the tubular element, the cutouts of the end effector elements rotatably and slidably engage with corresponding cam pins and via the force-application pin have their force-applying portions driven towards each other or moved apart. In another aspect of this invention, pairs of cooperating end effector elements for performing specific surgical operations are stored in modular contamination-resistant containers from which they can be moved to engage directly with the inner and outer elements of the surgical instrument for use. Used end effector elements can be put in a disengagement position by movement of the inner element within the outer tubular element and may be removed.