A medical device for removing tissue from a subject, comprising: a distal housing configured with a tissue cutter assembly; an elongate member coupled to the distal housing and configured to introduce the distal housing to a target tissue site of the subject, the elongate member having an outer tube, an inner drive tube rotatably mounted within the outer tube to rotate about a longitudinal axis of the elongate member, the inner drive tube having a crown gear located on a distal end thereof; a first rotatable member and a second rotatable member each rotatably mounted to the tissue cutter assembly, the first and the second rotatable members each comprising a plurality of disc shaped blades, wherein each of the plurality of blades of the first rotatable member lies in a plane parallel to and axially offset from a plane of another of the blades of the first rotatable member, each of the plurality of blades of the first and the second rotatable members being directly adjacent to at least one parallel surface and positioned to partially overlap the adjacent parallel surface such that tissue may be sheared between the adjacent, overlapping blades and parallel surfaces and such that the first and the second rotatable members are configured to rotate and direct tissue into an interior portion of the distal housing; characterised by a first drive gear train coupled between the crown gear and the first rotatable member, the first drive gear train consisting of a first spur gear and a second spur gear, wherein the first spur gear is configured to directly mesh with the crown gear and rotate about a first axis that is perpendicular to the longitudinal axis, and the second spur gear is configured to directly mesh with the first spur gear and rotate about a second axis that is perpendicular to the longitudinal axis; and a second drive gear train coupled between the crown gear and the second rotatable member, the second drive gear train consisting of a third spur gear and a fourth spur gear, wherein the third spur gear is configured to directly mesh with the crown gear and rotate about a third axis that is perpendicular to the longitudinal axis, and the fourth spur gear is configured to directly mesh with the third spur gear and rotate about a fourth axis that is perpendicular to the longitudinal axis, wherein the first and the second drive gear trains are configured to drive the first and the second rotatable members (818, 820), respectively, in opposite directions. a distal housing configured with a tissue cutter assembly; an elongate member coupled to the distal housing and configured to introduce the distal housing to a target tissue site of the subject, the elongate member having an outer tube, an inner drive tube rotatably mounted within the outer tube to rotate about a longitudinal axis of the elongate member, the inner drive tube having a crown gear located on a distal end thereof; a first rotatable member and a second rotatable member each rotatably mounted to the tissue cutter assembly, the first and the second rotatable members each comprising a plurality of disc shaped blades, wherein each of the plurality of blades of the first rotatable member lies in a plane parallel to and axially offset from a plane of another of the blades of the first rotatable member, each of the plurality of blades of the first and the second rotatable members being directly adjacent to at least one parallel surface and positioned to partially overlap the adjacent parallel surface such that tissue may be sheared between the adjacent, overlapping blades and parallel surfaces and such that the first and the second rotatable members are configured to rotate and direct tissue into an interior portion of the distal housing; characterised by a first drive gear train coupled between the crown gear and the first rotatable member, the first drive gear train consisting of a first spur gear and a second spur gear, wherein the first spur gear is configured to directly mesh with the crown gear and rotate about a first axis that is perpendicular to the longitudinal axis, and the second spur gear is configured to directly mesh with the first spur gear and rotate about a second axis that is perpendicular to the longitudinal axis; and a second drive gear train coupled between the crown gear and the second rotatable member, the second drive gear train consisting of a third spur gear and a fourth spur gear, wherein the third spur gear is configured to directly mesh with the crown gear and rotate about a third axis that is perpendicular to the longitudinal axis, and the fourth spur gear is configured to directly mesh with the third spur gear and rotate about a fourth axis that is perpendicular to the longitudinal axis, wherein the first and the second drive gear trains are configured to drive the first and the second rotatable members (818, 820), respectively, in opposite directions.