Osteogenesis by chondrocytes from growth cartilage of rat rib.

Chondrocytes were isolated from growth and resting cartilage of rat rib and cultivated in vitro. The cultivated chondrocytes were placed in Millipore diffusion chambers, which were then implanted into the abdominal cavities of rats for several weeks and prepared for histological analysis. The results indicate that growth cartilage cells have a remarkable osteogenic potential, even after cultivation in vitro, whereas resting cartilage cells show no osteogenic activity. However, growth cartilage cells alone do not form new bone but require the participation of certain host cells to initiate osteogenic differentiation.