Tissue thickness compensator comprising capsules defining a low pressure environment

A staple cartridge, comprising:

• a cartridge body comprising staple cavities;
• staples removably positioned with said staple cavities, wherein said staples are ejectable from said staple cavities;
• and
• a compensator comprising a vessel, wherein said vessel defines a sealed inner cavity, wherein said sealed inner cavity contains an inner atmosphere, wherein said inner atmosphere has a pressure less than atmospheric pressure when said vessel is in an unruptured state.

A staple cartridge, comprising:

• a cartridge body comprising staple cavities;
• staples removably positioned with said staple cavities, wherein said staples are ejectable from said staple cavities;
• and
• a compensator comprising a plurality of vessels, wherein each said vessel defines a sealed inner cavity, wherein each said sealed inner cavity contains an inner atmosphere, and wherein each said inner atmosphere has a pressure less than atmospheric pressure when said vessels are in an unruptured state.