Paraffin-embedded sections were histochemically stained with H&E or Alcian blue. For immunohistochemical analysis, immunolabeled sections using primary antibodies at 4°C overnight, including antibody to type II collagen (mouse IgG1, 1 μg/mL; Chemicon International, Temecula, CA), rabbit antibodies to aggrecan (10 μg/mL, Millipore, Billerica, MA), and antibody to Sox9 (rabbit IgG, 2.5 μg/mL; Abcam, Cambridge, MA), and horseradish peroxidase (HRP)-conjugated secondary (1:200; Santa Cruz Biotechnology, Santa Cruz, CA) antibodies for 1 hour. The DAB reagent (diaminobenzidine tetrahydrochloride) was subsequently used to detect the immunoactivity. The sections were counterstained with hematoxylin.