Inhibitory activity of cartilage growth in serum of young rats.

Humoral factors play an important role in growth regulation. The growth regulatory activity in serum is a complex system with both growth-promoting and growth-inhibiting factors. In this study, using in vitro cartilage from rat nasal septum as target organ, evidence is presented that inhibiting activity does exist in normal rat serum. This activity seems to play a role in modulating cartilage growth rate in young, normal animals. Furthermore, a significant interaction between age in cartilage and age in serum as regards influence on cartilage growth was found.