Figure 7. BMP-2 (A, C, E, G) and Aggrecan (B, D, F, H) immunohistochemistry. Intracellular BMP-2 is detectable in all ICRS grades whereas extracellular BMP-2 only can be found in osteoarthritic cartilage (E, ICRS: 2); Aggrecan could be detected in the ECM of normal and osteoarthritic cartilage. A decrease of Aggrecan immunolocalisation beginning in the upper layer occurs with increasing ICRS grade (D, F, H) whereas the appearance of intracellular Aggrecan seems to increase (F, H) and often is associated with extracellular BMP-2 (E, F), original magnification: 2.5x.