A tissue resecting instrument, comprising: a handpiece assembly including a drive rotor and an outflow conduit; and an end effector assembly configured to releasably engage the handpiece assembly, the end effector assembly comprising: an outer shaft; an inner shaft disposed within the outer shaft and configured to rotate and reciprocate relative to the outer shaft for cutting tissue; and an inner core drive assembly, including: a proximal receiver configured to receive a rotational input from the drive rotor and to rotate in response thereto, the proximal receiver including a seal member (160, 1160) disposed thereon; and a connector operably coupled to the proximal receiver such that the rotation of the proximal receiver effects rotation of the connector and reciprocation of the connector between a proximal position and a distal position, the connector operably coupled to the inner shaft such that the rotation and reciprocation of the connector effects the rotation and reciprocation of the inner shaft, the connector defining a cavity disposed in fluid communication with an interior of the inner shaft, characterized in that, in the proximal position, the connector abuts the seal member (160, 1160) to establish a seal that blocks outflow from the cavity into the outflow conduit, and wherein, in the distal position, the connector is displaced from the seal member (160, 1160) to permit outflow from the cavity into the outflow conduit. a handpiece assembly including a drive rotor and an outflow conduit; and an end effector assembly configured to releasably engage the handpiece assembly, the end effector assembly comprising: an outer shaft; an inner shaft disposed within the outer shaft and configured to rotate and reciprocate relative to the outer shaft for cutting tissue; and an inner core drive assembly, including: a proximal receiver configured to receive a rotational input from the drive rotor and to rotate in response thereto, the proximal receiver including a seal member (160, 1160) disposed thereon; and a connector operably coupled to the proximal receiver such that the rotation of the proximal receiver effects rotation of the connector and reciprocation of the connector between a proximal position and a distal position, the connector operably coupled to the inner shaft such that the rotation and reciprocation of the connector effects the rotation and reciprocation of the inner shaft, the connector defining a cavity disposed in fluid communication with an interior of the inner shaft, characterized in that, in the proximal position, the connector abuts the seal member (160, 1160) to establish a seal that blocks outflow from the cavity into the outflow conduit, and wherein, in the distal position, the connector is displaced from the seal member (160, 1160) to permit outflow from the cavity into the outflow conduit. an outer shaft; an inner shaft disposed within the outer shaft and configured to rotate and reciprocate relative to the outer shaft for cutting tissue; and an inner core drive assembly, including: a proximal receiver configured to receive a rotational input from the drive rotor and to rotate in response thereto, the proximal receiver including a seal member (160, 1160) disposed thereon; and a connector operably coupled to the proximal receiver such that the rotation of the proximal receiver effects rotation of the connector and reciprocation of the connector between a proximal position and a distal position, the connector operably coupled to the inner shaft such that the rotation and reciprocation of the connector effects the rotation and reciprocation of the inner shaft, the connector defining a cavity disposed in fluid communication with an interior of the inner shaft, characterized in that, in the proximal position, the connector abuts the seal member (160, 1160) to establish a seal that blocks outflow from the cavity into the outflow conduit, and wherein, in the distal position, the connector is displaced from the seal member (160, 1160) to permit outflow from the cavity into the outflow conduit. a proximal receiver configured to receive a rotational input from the drive rotor and to rotate in response thereto, the proximal receiver including a seal member (160, 1160) disposed thereon; and a connector operably coupled to the proximal receiver such that the rotation of the proximal receiver effects rotation of the connector and reciprocation of the connector between a proximal position and a distal position, the connector operably coupled to the inner shaft such that the rotation and reciprocation of the connector effects the rotation and reciprocation of the inner shaft, the connector defining a cavity disposed in fluid communication with an interior of the inner shaft, characterized in that, in the proximal position, the connector abuts the seal member (160, 1160) to establish a seal that blocks outflow from the cavity into the outflow conduit, and wherein, in the distal position, the connector is displaced from the seal member (160, 1160) to permit outflow from the cavity into the outflow conduit.