Morphogenetic potential of rat growth cartilages as isogeneic transplants in the interparietal suture area.

The proximal end of the tibia or the spheno-occipital synchondrosis with some adjoining bone were isogeneically transplanted across the interparietal suture of 10-day-old rats. As a sham procedure, a piece of calvarium traversed by a part of the interparietal suture was interchanged between pairs of animals. Untreated rats served as controls. The animals, injected with Alizarin red S, were killed 25-75 days after the operation, 10 in each group. The transverse dimensions of the neurocranium were larger in the rats with the cartilage transplants than in the controls, particularly at 25 days after the operation; the differences persisted longer in the animals with the synchondroseal transplant. The orientation of the bone interdigitation at the anterior lambdoidal suture changed temporarily in response to the excessive lateral displacement of the parietal bones. The observations indicate that basicranial synchondroses, like epiphyseal cartilage, are endowed with a tissue-separating property that may persist for a prolonged period under transplant conditions. As such cartilaginous structures may also be affected by environmental influences, there must be a two-way interaction between the synchondroses and their immediate environment.