Synovial fluid is secreted by which cells in the synovium?

• A. Fibroblasts
• B. Macrophages
• C. Synoviocytes
• D. Chondrocytes

Answer: (C)

Synoviocytes—the cells that line the synovial membrane—are responsible for secreting the synovial fluid. They come in two main subtypes: fibroblast-like synoviocytes (type B) that produce hyaluronic acid and other lubricating molecules, giving the fluid its viscoelastic, lubricating properties, and macrophage-like synoviocytes (type A) that help with immune functions and debris clearance. The fluid nourishes avascular cartilage and reduces joint friction, so the secretion target is the synovial lining itself. Chondrocytes are cartilage cells and do not secrete synovial fluid, and while macrophage-like cells are present, the key secretors of the lubricating fluid are the synoviocytes.