Chondrocytes are the resident cells of cartilage and are responsible for synthesizing a range of extracellular matrix macromolecules. These include collagen type II, aggrecan, link protein, collagen type IX, and collagen type XI. The control of proliferation and differentiation of chondrogenic cells is central to the coordinated development of the vertebrate skeleton. Chondrocytes are capable of producing and responding to a large number of peptide growth factors and cytokines, including both, insulin-like growth factor-1 and interleukin-1. Articular cartilage covers the diarthrodial joints and is responsible for the mechanical distribution of loads across the joints. Chondrocytes control the majority of its structure and function that regulate Extracellular Matrix (ECM) turnover and maintain tissue homeostasis. Rat Chondrocytes are useful in vitro models for studying cartilage regeneration and repair; but also cytokine and growth factor effects on cartilage, specific gene regulation and pathophysiology of arthritis.