Retardative effects of a corticosteroid hormone upon chondrocyte growth in the mandibular condyle of neonatal mice.

This study examined the influence of triamcinolone hexacetonide, a long-acting synthetic analog of cortisol on the proliferative activity and subsequent development of chondroprogenitor cells in condylar cartilage of neonatal mice. It became evident that a single injection of relatively low doses of the hormone significantly reduced the uptake and incorporation of [3H]thymidine followed by a significant decrease in the number of young cartilage cells. A unique feature was the fact that at the same time condyles of triamcinolone-treated mice revealed an increase in the number of mesenchyme-like cells within the condylar chondroprogenitor zone. High values of correlation were noted between the inhibitory effects of the hormone upon the incorporation of [3H]thymidine, the number of mitotic figures (within the chondroprogenitor zone), and the dimension of the chondroblastic zone. This study indicates that in young animals fluorinated corticosteroid hormones possess a significant bivalent inhibitory effect upon both the proliferative activity of chondroprogenitor cells as well as upon capacity of the latter cells to differentiate into chondroblasts. In so doing, corticosteroids adversely affect the normal process of endochondral bone formation in one of the prominent growth centers within the craniofacial skeleton. Thus, in the developing animal, corticosteroids impair the growing mandible from expressing its inherent morphogenetic pattern.