Development of cartilage in transplanted future coronal sutures

From fetal rat skulls, tissue containing the 19-day-old presumptive coronal suture was excised and transplanted onto the exposed dura mater of adult rats. Host animals were sacrificed after 1, 2, 3, 4, 5 and 6 days. From the results of these experiments, the following conclusions can be drawn: (1) in all transplants chondrogenic activity occurred, resulting in the production of ectopic cartilage, and (2) cartilage development only starts on the cerebral side of the transplanted embryonic dura mater just beneath the area of the presumptive suture. Transplanted presumptive sutures of 21-day-old rats do not produce cartilage. The findings suggest that the suture undergoes a process of maturation. The existence of an osteogenesis-inhibiting mechanism, located in embryonic sutural tissue and being transmitted to the developing dura, is discussed.