Fig. 6. Expression of Wnt inhibitors in E7.5 embryos. Wild-type embryos are on the left, Ldb1^-/- mutants on the right. (A,B) Frzb expression. Expression is undetectable in the primitive streak and the prospective cardiac mesoderm regions of the mutant. (C,D), Expression of Sfrp1. The signal is greatly reduced in the anterior ectoderm of the mutant. (E,F) Expression of Sfrp2. This signal is absent in the mutant. (G,H) Cer1 expression. The signal, marking the AVE, the axial mesendoderm and the definitive endoderm of late streak embryos, is absent in the mutant. (I) Variation in the expression level of the Cer1 gene in Ldb1 mutant and wild-type embryos. The scale bar represents 100 µm.