Individual canine synovial villi were used to establish short-term synovial organ cultures. These villi incorporated 3H-glucosamine into highly-polymerized 'H-hyaluronic acid (3H-HA), which was the only 3Hglycosaminoglycan identified in the culture medium. Some 3H-HA, and larger amounts of other 3H-glycosaminoglycans, were recovered from cultured tissues. Culture medium 3H-HA content was proportional to the surface area of cultured villi. Organ cultures of nonvillous synovium were compared with villi; nonvillous cultures synthesized less 'H-HA per mmz of their synovial intimal surface than villi. These cultures complement cell culture techniques for in vitro studies of synovial lining cell function.
The first synovial tissue cultures contained minced synovial membranes, which were observed for brief periods as organ cultures (1). Most recent investigations of the synovium in vitro have utilized monolayer cultures of "synovial cells." Whether obtained from the synovial membrane by enzyme digestion or derived from outgrowths of explanted membranes, these cells have been shown to synthesize hyaluronic acid (HA), smaller quantities of sulfated glycosaminoglycans (GAGS), and a number of proteins (2). Both