Fig. 1. Morphological changes of chondrocytes in culture. Chondrocytes isolated from the ribs of wild-type (A-C) and Runx2^–/– (D-F) embryos at E18.5 were inoculated in DMEM/F12 hybrid medium containing 10% FBS at a density of 1x10⁵/plate in 24-well plates, and cultured for up to 9 days. Phase-contrast images at days 3, 6 and 9 (with day 0 as the day of plating) are shown. Magnification, x50.