A staple cartridge for use with a surgical stapler, said staple cartridge comprising: a cartridge body, comprising: a proximal end; a distal end; a support portion; and a plurality of staple cavities (10012; 11212) defined within said support portion (10010; 11210), wherein each said staple cavity (10012; 11212) comprises an opening in said support portion (10010; 11210); a plurality of guide cleats (10013; 11213) extending from said support portion (10010; 11210), wherein each said guide cleat (10013; 11213) comprises at least one guide groove (10016; 11216); and an implantable compressible portion positioned adjacent to said support portion (10010; 11210), wherein said guide cleats (10013; 11213) are at least partially embedded in said compressible portion; and a plurality of staples, wherein at least a portion of each said staple is removably stored within a said staple cavity (10012; 11212), wherein each said staple is movable between an unfired position and a fired position, wherein each said staple is deformable between an unfired configuration and a fired configuration when each said staple is moved between said unfired position and said fired position, wherein each said staple comprises at least one deformable leg removably positioned in a said guide groove (10016; 11216) when said staple is in said unfired position, and wherein said compressible portion is configured to be captured within said staples when said staples are deformed between an unfired configuration and a fired configuration. a cartridge body, comprising: a proximal end; a distal end; a support portion; and a plurality of staple cavities (10012; 11212) defined within said support portion (10010; 11210), wherein each said staple cavity (10012; 11212) comprises an opening in said support portion (10010; 11210); a plurality of guide cleats (10013; 11213) extending from said support portion (10010; 11210), wherein each said guide cleat (10013; 11213) comprises at least one guide groove (10016; 11216); and a proximal end; a distal end; a support portion; and a plurality of staple cavities (10012; 11212) defined within said support portion (10010; 11210), wherein each said staple cavity (10012; 11212) comprises an opening in said support portion (10010; 11210); a plurality of guide cleats (10013; 11213) extending from said support portion (10010; 11210), wherein each said guide cleat (10013; 11213) comprises at least one guide groove (10016; 11216); and an implantable compressible portion positioned adjacent to said support portion (10010; 11210), wherein said guide cleats (10013; 11213) are at least partially embedded in said compressible portion; and a plurality of staples, wherein at least a portion of each said staple is removably stored within a said staple cavity (10012; 11212), wherein each said staple is movable between an unfired position and a fired position, wherein each said staple is deformable between an unfired configuration and a fired configuration when each said staple is moved between said unfired position and said fired position, wherein each said staple comprises at least one deformable leg removably positioned in a said guide groove (10016; 11216) when said staple is in said unfired position, and wherein said compressible portion is configured to be captured within said staples when said staples are deformed between an unfired configuration and a fired configuration.