An anvil assembly, an end effector, and/or a surgical stapler are suitable for performing curved or circular anastomosis and/or treatment to internal walls of hollow tissue organs. The anvil assembly includes an anvil center rod and an anvil head secured to a distal end of the anvil center rod. The anvil head includes an anvil plate defining a tissue contact surface and a plurality of staple forming pockets formed in the tissue contact surface of the anvil plate. Each of the staple forming pockets defines an arcuate longitudinal axis.
