(a) Time-dependent changes in average percentage of TUNEL-positive chondrocytes in CF layer after surgery. The average percentages of TUNEL-positive chondrocytes in the resection group at 2 and 4 weeks were significantly higher than those in the sham group. The average percentage of TUNEL-positive chondrocytes at 2 week was significantly higher than those at 1 and 6 weeks. Shaded bars: Resection group, Unshaded bars: Sham group Safranin-O staining of histological sections of at 4 weeks in CF layer; (b): resection group, (d): sham group. (c) and (e) are magnified views of the boxed part in (b) and (d) that are TUNEL of histological sections at 4 weeks in CF layer. The TUNEL-positive chondrocytes are brown (arrow).