Fig. 2. Impaired chondrocyte differentiation and matrix deposition in vivo. (A) In vivo BrdU labeling of E19.0 embryos. The labeling index (BrdU positive cells/total cells) in zones of proliferating chondrocytes is shown. Bars represent mean value±s.d.; n=2; ^*P<0.001. (B) Ki67-positive cells in zones of proliferating chondrocytes at E14.5, E16.5 and E18.5. (C) Von Kossa staining of calcified matrix of E15.5 and E17.5 Fosl2^–/– embryos and littermate controls. Arrowheads indicate stained matrix in the zones of hypertrophic chondrocytes. Pictures were taken at 50x magnification.