Fig. 6

Representative histology images of tibial articular cartilage. A–D surgically induced group. E–H chemically induced group. Safranin O/fast green stained with 20× magnification. Apoptosis indicated by empty chondrons at week 4 and week 8 in the surgically induced group (red arrow). Superficial and upper mid-zone erosion can be seen at week 12 in the surgically induce group (arrowhead). For the chemically induced group, a lack of chondrocytes can be seen at week 4 (asterisk) and complete erosion at week 12