Little is known concerning the origin and functions of the synovial fluid which has not been the subject of extensive chemical investigation. It is more or less evident that the synovial fluid plays a lubricating rôle in joint structures by virtue of its content of mucin, but to what extent, if at all, it serves as a nutritive medium is not clearly established. In view of the fact that articular cartilage has a small blood supply, the synovial fluid has been regarded as aiding in its growth and nutrition. William Hunter first demonstrated in connection with articular cartilage the existence of the circulus articuli vasculosus but this system supplies only the lateral aspects, leaving the bulk of articular cartilage without direct blood supply. Gray1 refers to articular cartilage as a nonvascular structure.
More than eighty years ago, Toynbee advanced the view that articular cartilage derives its chief pabulum from the