Figure 2

Local bone erosion starts from the junction of the cartilage, the bone and the synovial membrane. Histological sections of knee joints of hTNFtg mice stained by (a, b) hematoxylin and eosin, (c, d) tartrate-resistant acid phosphatase and (e, f) toluidine blue. Microphotographs show an overview of the knee joint ((a), (c), (e), original magnification, 25 ×) and close-ups of the junction zone ((b), (d), (f), original magnification, 100 ×). Note synovial inflammatory tissue at the junction zone (arrow in (b)), invading the subchondral bone by osteoclast-mediated bone resorption (arrow in (d)), and leading to proteoglycan loss of the articular cartilage (arrow in (f)).