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Fig. 2 Bmp4 is required in the establishment of chordamesoderm during late gastrulation. (A,B,H,I,O,P,V,W) Morpholino knockdown of Fstl1 and Fstl2 has no effect on the development of axial structures prior to 70% epiboly. (C-F,J-M,Q-T,X-AA) At 90% epiboly, alteration of BMP signaling reveals a requirement for BMP activity in patterning of chordamesoderm. (G,N,U,BB) The chordamesoderm phenotype observed when Fstl1/2 and Bmp4 are knocked down in concert resembles that of Bmp4 morphants. Arrows in C-G and K-N,R-U,Y indicate the extent of prechordal plate and chordamesoderm domains, respectively. gsc (C-G) expression in prechordal plate, and flh (J-N), ntl (Q-U) and admp (X-BB) expression in chordamesoderm. (A-G,O,P) Views are lateral, with ventral towards the left. Insets in A-G are dorsal views of the prechordal plate domain. Insets in O,P are dorsal views of chordamesodermal domain. All other views are dorsal views, with anterior towards the top. Scale bar in A: 100 μm in all panels.