An end effector comprising: a first jaw member comprising a first jaw body, a first tissue gripping element, a first clamping plane, a first positively-angled tissue-contacting surface, and a first negatively-angled tissue-contacting surface, wherein the first tissue gripping element has a planar tissue contact surface, wherein the first positively-angled tissue-contacting surface is at an angle (α) away from the first clamping plane and away from the first jaw body at the periphery of the first tissue gripping element, and wherein the first negatively-angled tissue-contacting surface is at an angle (α) away from the first clamping plane and toward the first jaw body at the periphery of the first tissue gripping element; and a second jaw member comprising a second jaw body, a second tissue gripping element, a second clamping plane, a second positively-angled tissue-contacting surface, and a second-negatively angled tissue-contacting surface, wherein the second tissue gripping element has a planar tissue contact surface, wherein the second positively-angled tissue-contacting surface is at an angle (α) away from the second clamping plane and away from the second jaw body at the periphery of the second tissue gripping element, and wherein the second negatively-angled tissue-contacting surface is at an angle (α) away from the second clamping plane and toward the second jaw body at the periphery of the second tissue gripping element; wherein the first jaw member is movable relative to the second jaw member between an open position and a closed position; and wherein the first positively-angled tissue-contacting surface opposes the second negatively-angled tissue-contacting surface when the first and second jaw members are in the closed position, and wherein the first negatively-angled tissue-contacting surface opposes the second positively-angled tissue-contacting surface when the first and second jaw members are in the closed position; wherein two opposed angled tissue-contacting surfaces form a common angle (α1, α2) relative to their respective clamping planes. a first jaw member comprising a first jaw body, a first tissue gripping element, a first clamping plane, a first positively-angled tissue-contacting surface, and a first negatively-angled tissue-contacting surface, wherein the first tissue gripping element has a planar tissue contact surface, wherein the first positively-angled tissue-contacting surface is at an angle (α) away from the first clamping plane and away from the first jaw body at the periphery of the first tissue gripping element, and wherein the first negatively-angled tissue-contacting surface is at an angle (α) away from the first clamping plane and toward the first jaw body at the periphery of the first tissue gripping element; and a second jaw member comprising a second jaw body, a second tissue gripping element, a second clamping plane, a second positively-angled tissue-contacting surface, and a second-negatively angled tissue-contacting surface, wherein the second tissue gripping element has a planar tissue contact surface, wherein the second positively-angled tissue-contacting surface is at an angle (α) away from the second clamping plane and away from the second jaw body at the periphery of the second tissue gripping element, and wherein the second negatively-angled tissue-contacting surface is at an angle (α) away from the second clamping plane and toward the second jaw body at the periphery of the second tissue gripping element; wherein the first jaw member is movable relative to the second jaw member between an open position and a closed position; and wherein the first positively-angled tissue-contacting surface opposes the second negatively-angled tissue-contacting surface when the first and second jaw members are in the closed position, and wherein the first negatively-angled tissue-contacting surface opposes the second positively-angled tissue-contacting surface when the first and second jaw members are in the closed position; wherein two opposed angled tissue-contacting surfaces form a common angle (α1, α2) relative to their respective clamping planes.