Fig. 7. Evc-deficient mice show premature hypertrophic differentiation of proliferating chondrocytes. (A) Analysis of chondrocyte proliferation. On the left, E17.5 wild-type and mutant proximal tibia sections, stained with BrdU immunhistochemistry; the rectangles indicate the areas of columnar chondrocytes that were counted. On the right, bar chart showing that the percentage of BrdU-positive cells in the proliferating zone does not significantly differ between wild type and mutant (ANOVA, P=0.2374). (B) Expression of differentiation markers Col2a1, Col10a1, Pthrp and PPR in E16.5 wild-type and mutant embryos. The region of Pthrp expression is outlined by the dashed line. Note the absence of PPR signal in the perichondrium adjacent to late proliferating and early prehypertrophic chondrocytes in Evc^-/- sections (arrowheads). (C) Comparative analysis of Fgfr3 and Fgfr1 expression pattern in wild-type and mutant E16.5 distal tibiae. There is no difference in Fgfr1 expression, but marked shortening of the Fgfr3 expression domain. The boxed areas of the left-hand panels are shown at high mignification in the middle panels for Fgfr3 and in the right-hand panels for Fgfr1.