Establishment of a whole-chick sternum model that recapitulates normal cartilage development.

A serum-free organ culture model for chondrocyte maturation, using the Avian sternum, was developed. Day-14 chick embryo sterna were placed in organ culture in the presence of defined medium. The optimal medium for chondrocyte terminal differentiation contained specific concentrations of dexamethasone, insulin, thyroid hormone and ascorbic acid. Three parameters, including sternal growth, cell diameter and type X collagen production, were analyzed as indicators of chondrocyte terminal differentiation. These parameters were analyzed in cephalic, middle and caudal regions of the organ-cultured chick sterna and compared to sterna grown in ovo. This study demonstrates that the organ-cultured tissue maintains normal morphological characteristics and terminal differentiation in the cephalic region only, similar to in ovo development, while maintaining normal cell-matrix relationships.