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Fig. 2 Wnt8 is not required for BMP expression. In situ hybridizations at -70% epiboly to detect expression of bmp2b (A-D), bmp4 (E-H), and bmp7 (I-L). Shown are lateral views, anterior up, dorsal right. Genotypes are indicated above each row. A,E,I: bmp2b, bmp4, and bmp7 are expressed in the ventral embryo. Arrows indicate the dorsal limit of the observable signal for each ligand. B,F,J: Ventral BMP expression is significantly reduced in wnt8 mutant embryos, indicated by ventral shift in position of arrow. Ventral ectoderm bmp2b expression is not as significantly affected (white asterisk). C,G,K: Chordin knockdown leads to dorsal expansion of BMP expression. Note dorsal shift of arrow positions. D,H,L: BMP ligand expression is dorsally expanded in wnt8 mutants that have Chordin knocked down. Note the expanded ventral ectoderm domain of bmp2b in wnt8;chordin double loss-of-function (asterisk in D), compared to wnt8 mutant (asterisk in B). While bmp2b in the margin does not appear to recover in the double loss-of-function (arrow in D), both bmp4 and bmp7 show dorsally expanded expression in the double loss-of-function.