“…Since the histological components of synovial membranes are shared by 578 tendon sheaths and certain other connective tissues, we are not of the opinion that all giant cell tumors of this type must of necessity arise from synovial membranes or tendon sheaths. In fact, more or less histologically similar tumors have been described as arising from peritendinous connective tissue (Kobak and Perlow, 1949) and from periosteum (Seth, Majid and Rao, 1964). The orientation of stromal cells about central areas of degeneration, seen in the hamster tumors, may represent abortive attempts at joint formation.…”