Glucocorticoid hormone adversely affects the growth and differentiation of cartilage cells in neonatal mice.

Condylar cartilage of neonatal mice served as an experimental model to study the late in vivo effects of a single dose of a fluorinated synthetic analogue of cortisol on cartilage cell growth and development. Forty-eight hours after the administration of triamcinolone hexacetonide, the proliferative rate of chondroprogenitor cells decreased significantly. However, by the 6th day a marked recovery took place when the total number of 3H-thymidine labelled cells increased by 52.9%, and by 13 days hormone-treated condyles revealed an increase of 93.1% in the total number of labelled cells. At the same time, the magnitude of the chondroprogenitor zone increased by 194.4% and it was found to contain a large population of fibroblast-like cells. The latter were found to synthesize type I collagen and fibronectin, lacked any specific organization and occupied larger portions of the condylar head. Twenty days following the administration of the hormone the newly-formed mass of fibroblast-like cells penetrated the underlying cartilage, split it and formed a direct communication with the marrow cavity. Ultrastructural examination further substantiated the fibroblastic nature of the newly-formed cell population. Hence, it seems very possible that if a corticosteroid hormone is administered to newborn animals it possesses the capacity to affect the normal differentiative pathway of pre-chondroblasts and shift their developmental pathway toward the fibroblastic cell line.