Self contained gas powered surgical apparatus

A self contained gas powered endoscopic surgical apparatus is provided placing lateral lines of surgical fasteners into body tissue. The apparatus includes an anvil member and a surgical fastener cartridge member mounted to the distal end of an elongated endoscopic portion. A tubular collar of the endoscopic portion moves distally to engage the anvil member and bias the anvil member and the cartridge member into cooperative alignment, thereby clamping body tissue to be fastened between the anvil member and the cartridge member. A self contained pneumatic system is disposed in the surgical apparatus and is actuable to eject and/or form the surgical fasteners in the clamped body tissue. The apparatus further comprises a mechanism for preventing the premature actuation of the pneumatic system during shipment of the instrument. A mechanism for frictionally engaging body tissue inserted between the anvil member and the cartridge is also provided. In addition, a mechanism for inhibiting external exposure of a tissue cutting structure is provided.