A cartridge assembly for selective connection to a surgical stapling apparatus includes a body portion, a tissue contact surface defining staple retention slots, staples, a collar assembly and a staple sheath. Each of the staples is received in a respective one of the staple retention slots of the tissue contact surface. The collar assembly is movably mounted to the body portion. The staple sheath is coupled to the collar assembly and positioned to cover the staple retention slots. The staple sheath is selectively movable relative to the tissue contact surface.