Fig. 1. Reduced zones of hypertrophic chondrocytes in Fosl2^–/– embryos and newborn mice. (A) Skeletal staining of a Fosl2^–/– newborn and wild-type littermate at P0. (B) Length of mineralized regions of knock-out and wild-type littermates at P0; bars represent mean value±s.e.m.; n=4. (C) Genotyping-PCR of DNA from wild-type, heterozygous and Fosl2-null newborn mice. (D) Expression of Fosl2 in primary rib cage chondrocytes and its absence in mutant cells. Primary chondrocytes were cultured for 3 days prior to RNA isolation and RNase protection assay. GAPDH was used as loading control. (E) Real-time PCR of cartilage markers. Relative expression of type X collagen (colX), aggrecan (agg) and Ihh is shown. Expression levels were normalized to tubulin expression. The mean of two independent measurements is shown. (F) In situ hybridization on sections of embryonic and postnatal femoral growth plates of Fosl2^–/– mice and littermate controls using a type X collagen antisense probe as a marker for hypertrophic zones. Pictures were taken at 200x (E13.5), 100x (E14.5, E16.5, E18.5) and 50x (P2, P4) magnification.