Figure 1. Cartilage grafts for segmental defect healing.
The generation of an unstable fracture (1) in mouse A produces a lot of cartilage in the soft callus tissue by day 7 (2). The explanted fracture callus/cartilage is made into a graft (3), and transplanted (4) into a tibial segmental defect in mouse B that heals with external fixation. During this healing process (5), the grafted chondrocytes de-differentiate into Oct4+ progenitor cells, and then differentiate into hypertrophic chondrocytes, osteoblasts and osteocytes in the regenerate tissue. Abbreviations: col II, type II collagen; col X, type 10 collagen; OC, osteocalcin; Oct4, octamer-binding protein 4.