A loading unit (116, 216, 316, 416) for use with a surgical stapling apparatus, the loading unit comprising: a tool assembly having a cartridge assembly (118, 418) including a staple cartridge (182, 482) having a plurality of surgical fasteners therein, and an anvil assembly (120, 220, 320), at least one of the cartridge assembly and the anvil assembly being movable in relation to the other of the cartridge assembly and anvil assembly, wherein the anvil assembly includes an anvil plate (170, 270, 370) and, wherein each of the anvil plate and the staple cartridge define an elongate longitudinal slot (170b, 182c, 270b, 370b, 482c); a surgical buttress releasably secured to a tissue contacting surface of at least one of the anvil plate and the staple cartridge, wherein each surgical buttress is secured to the at least one of the anvil assembly and the cartridge assembly by at least one anchor wherein at least one of the anvil assembly and the cartridge assembly includes a constricting, open-ended, side slot (170e, 182f, 270e, 370e, 482f) configured to grip an end of the anchor; a release assembly (174, 194, 274, 374, 494) associated with the at least one of the anvil assembly and the cartridge assembly; and a drive assembly (150, 250, 350, 450) slidably translatable through the tool assembly from a proximal position to a distal position, the drive assembly actuating the release assembly to thereby release the anchor to free the surgical buttress from the at least one of the anvil assembly and cartridge assembly, characterized in that the release assembly is configured to push the end of the anchor out of the side slot, upon a distal advancement of the drive assembly. a tool assembly having a cartridge assembly (118, 418) including a staple cartridge (182, 482) having a plurality of surgical fasteners therein, and an anvil assembly (120, 220, 320), at least one of the cartridge assembly and the anvil assembly being movable in relation to the other of the cartridge assembly and anvil assembly, wherein the anvil assembly includes an anvil plate (170, 270, 370) and, wherein each of the anvil plate and the staple cartridge define an elongate longitudinal slot (170b, 182c, 270b, 370b, 482c); a surgical buttress releasably secured to a tissue contacting surface of at least one of the anvil plate and the staple cartridge, wherein each surgical buttress is secured to the at least one of the anvil assembly and the cartridge assembly by at least one anchor wherein at least one of the anvil assembly and the cartridge assembly includes a constricting, open-ended, side slot (170e, 182f, 270e, 370e, 482f) configured to grip an end of the anchor; a release assembly (174, 194, 274, 374, 494) associated with the at least one of the anvil assembly and the cartridge assembly; and a drive assembly (150, 250, 350, 450) slidably translatable through the tool assembly from a proximal position to a distal position, the drive assembly actuating the release assembly to thereby release the anchor to free the surgical buttress from the at least one of the anvil assembly and cartridge assembly, characterized in that the release assembly is configured to push the end of the anchor out of the side slot, upon a distal advancement of the drive assembly.