In vitro culture of rabbit growth plate chondrocytes. 2. Chondrodystrophic mutants

The epiphyseal plates of newborn normal (Cd/?), dwarf (Dw/Dw) and achondroplastic (ac/ac) rabbits were grown in organ culture for 48 hours. The 3H-thymidine labeling index of proliferating zone chondrocytes from both mutants was below that of normals. The generation time of Dw/Dw animals was longer than that of normals (greater than 24 vs. 17 hours respectively). Inasmuch as the medium was supplemented with 10% fetal calf serum, which presumably contains somatomedin, these data suggest that the Dw/Dw mutant cannot be considered simply a model for pituitary dwarfism. Pituitary fibroblast growth factor (FGF), 50ng/ml, decreased the labeling index of chondrocytes from both Dw/Dw and ac/ac animals. Thus neither a lack of FGF nor an end-organ non-responsiveness to this factor seems to play a role in the pathogenesis of either growth disturbance.