CHANGES IN THE EXPRESSION OF FIBROBLAST GROWTH-FACTOR RECEPTORS MARK DISTINCT STAGES OF CHONDROGENESIS IN-VITRO AND DURING CHICK LIMB SKELETAL PATTERNING

Members of the fibroblast growth factor (FGF) family of growth factors are key regulators of limb skeletal patterning and growth. Abnormal e xpression of FGFs or mutations in their receptors (fgfrs) result in sk eletal disorders. Here we show that changes in the expression of fgfrs are intrinsic properties of differentiating cartilage. In mesenchymal micromass cultures differentiating into cartilage, as in ovo, fgfr 1 mRNA was found predominantly in undifferentiated, proliferating mesenc hyme, fgfr 2 in precartilage cell aggregates, and fgfr 3 in differenti ating cartilage nodules. Thus, our data suggest that switches in the e xpression of fgfr 1, 2, and 3 mRNAs are associated with phases of cart ilage patterning both in vitro and in ovo, and mark distinct stages in the development of the limb skeleton. (C) 1995 Wiley-Liss, Inc.