✓ A study was carried out to determine the separability of costochondral tissue and to investigate the preservation of its integrity as a transplant to a relatively immobile osseous site. On 10-day-old rats, two autogenous rib sections, complete with bone and cartilage, were transplanted across the interparietal suture with the cartilaginous ends either in the same direction or in opposite directions; untreated rats were used as controls. The animals, injected with Alizarin red S, were killed 25, 50, and 75 days after the operation, 10 at each time. At 25 days after the operation the calvarial width and neurocranial height were significantly greater, and the strip of new white bone appeared wider in the experimental animals as compared to the untreated control rats; later, the differences were less pronounced. The changes in the neurocranial morphology seemed more symmetrical following positioning of the cartilaginous ends of the graft in opposite directions than when they were in the same direction. In some transplants the endochondral ossification process appeared normal at the termination of the experimental period, but signs of degeneration were also observed. The findings were considered to indicate that costochondral transplants are endowed with an intrinsic tissue-separating capacity, and that they can preserve their integrity for an extended period under relatively nonfunctional conditions.
Regulation of Osteoarthritis Development by Wnt–β-catenin Signaling Through the Endochondral Ossification Process