What is this white part of these lamb chops called? What is the white part (circled in black) of these lamb chops called?  I know they contain fat, but is there a name for the tissue itself?  Do they occur throughout the meat or is it only in certain parts?  I believe back lamb racks don't contain them, but the front ones do.  Is this correct?
It's hard to tell from your photo, but probably fat or connective tissue.