FIGURE 1.
Apoptosis and related events in Hyp chondrocytes. A, histological examination of chondrocyte apoptosis. Hematoxylin/eosin staining (left) and TUNEL staining (right) were performed using tibias of 4-week-old WT and Hyp mice. The hypertrophic zone is marked with dotted lines, and the scale bars indicate 200 μm. Representative pictures obtained of numerous sections of four mice from each group are shown. B, number of TUNEL-positive cells in the tibial growth plates of WT and Hyp mice. C, quantitative determination of chondrocyte apoptosis. Cells were cultured in the differentiation medium in 96-well plates for 7 days. The determination was conducted using the cell death detection ELISAPLUS kit after differentiation. Data are shown as apoptotic activity. D, histochemical staining of WT and Hyp chondrocytes. Cells were cultured for 7 days in the differentiation medium and stained with Alcian blue for GAG synthesis (upper) and with alizarin red S for mineralization (lower). E, quantification of Alcian blue staining. F, quantification of alizarin red staining. Results are expressed as the mean ± S.E. of four separate experiments. *, significantly different from WT chondrocytes (p < 0.05).