Expression of molecular markers in the PrV detected by in situ hybridization. Transverse sections of the E14.5 PrV of wild-type (A,C,E,G)andDrg11-/-(B, D, F, H)embryos. A,B, Ebf1 expression is detected in the wild type (A), but not in the mutant (B). No significant changes are found in the expression pattern of Ebf2 (C,D), Ebf3 (E,F), and Rnx (G,H) between the wild-type and mutant PrV at E14.5. Scale bar, 100 μm.