Early repair processes in osteochondral defects. Gross appearance at (a) 3 weeks, (d) 6 weeks, and (g) 12 weeks. After 6 weeks of implantation, the surface of the defect was covered with cartilaginous white tissue. Micro-CT scanning at (b, c) 3 weeks, (e, f) 6 weeks, and (h, i) 12 weeks suggested that bone formations were present at the peripheral areas and developed toward the central area. (j) Gross appearance and (k, l) micro-CT scanning of a control rabbit without any implantation at 12 weeks. Although the gross appearance showed that the defect was filled with white tissues, the subchondral bone formation was incomplete at the center of the defect at 12 weeks. Downwards arrows indicate the borders of the defect. Representative subjects of two or three experiments for each time course are shown.