Fig. 6

PFD delayed progression of OA. Safranin O and Fast Green staining of the medial femoral condyles from different groups (a: scale bar of top row-1 mm; scale bar of bottom row-250 μm) and corresponding OARSI scores (b). Black arrows indicate the occurrence of chondrocyte clusters and increased cell numbers, observed in samples from the 4 and 12-week groups. Blue arrows indicate fissures on the surface of the cartilage, which were significantly more severe in the 12-week group, and loss of chondrocytes. Asterisks indicate erosion of the cartilage. There was fewer fissures or chondrocyte clusters in the PFD group. OARSI scores allowed semi-quantitation of cartilage degeneration. Data represent means ± SD. * P < 0.05, ** P < 0.01, *** P < 0.001 (4 and 12-week groups were compared with the control group; the PFD group was compared with the control and 12-week groups) (unpaired t-test)