Matrix formation in craniofacial cartilages of the rat. [35S]-sulfate incorporation studies.

Various cartilaginous zones in the craniofacial region of rats were studied using radioactive sulfate incorporation. Chondroitinsulfate represents a major part of the cartilaginous matrix. By measuring the cpm/DNA ratio in the tissue samples, one will get an expression of the matrix formation activity of the zones investigated. An increase in the cpm/DNA ratio was found in all zones between the 14th and the 17th day. This increase corresponds with a period of great proliferative activity. Autoradiography of the mandibular condyle revealed no sulfate labelling centrally indicating that this structure grows purely by surface apposition.