A comparative study on the growth of craniofacial cartilages in vitro

In order to evaluate the independent growth potential in a non-functional environment and the existence of a tissue separating growth force at different stages during postnatal development, craniofacial cartilages from 1, 4, 10, 16 and 21 day-old-rats were cultured for 10 days in a serum-free culture system. Using a specially designed in vitro pressure registration device the maximal growth pressure for each of the explants was determined. The following cartilages were studied: the mandibular condylar cartilage, the nasal septal cartilage, the cartilages of the cranial base and, for comparison with a somatic cartilage, the epiphyseal growth plate cartilage of the third metatarsal.For all explants, the amount of in vitro growth decreased during ageing: most sharply for mandibular condylar cartilage, more gradually for the others. The considerable differences in the in vitro maximal growth pressure values between the various cartilages persisted up to the age of 21 days. It became apparent that the maximal growth pressure value was not proportionally correlated to the rate and extent of in vitro growth. It was suggested that the differences in the in vitro maximal growth pressure values between the various cartilages are mainly structural, i.e. related to the external and internal structure of the cartilage involved.Although there are various restrictions in the application of in vitro values, the newly detected characteristics of the craniofacial cartilages contribute new information to the debate on the role of these structures in cranial growt