sünoviaalkude

Synovial tissue, known in Estonian as sünoviaalkude, is a specialized connective tissue found lining the articular capsule of synovial joints. It is responsible for producing synovial fluid, a viscous lubricant that reduces friction between the cartilage surfaces of the bones within the joint. This fluid also provides nutrients to the avascular articular cartilage and helps to absorb shock.

Histologically, synovial tissue is characterized by two main layers. The deeper layer, known as the subintima, is composed of fibroblasts and adipocytes, which provide structural support and store energy. The superficial layer, or intima, is a thin cellular layer containing synoviocytes. There are two types of synoviocytes: Type A cells, which are phagocytic and resemble macrophages, and Type B cells, which are more abundant and resemble fibroblasts, synthesizing and secreting the components of synovial fluid, including hyaluronic acid and lubricin.

The vascularity of synovial tissue is important for nutrient and waste exchange, although it does not extend into the joint cavity itself. Inflammation of the synovial tissue is known as synovitis, a common condition associated with various rheumatic diseases such as rheumatoid arthritis and osteoarthritis. Synovitis can lead to pain, swelling, and stiffness in the affected joints. The smooth, continuous nature of the synovial lining is crucial for efficient joint function and mobility.