Fig. 6. Fgf-mediated restriction of Bmp gene expression is essential for dorsoventral patterning. bmp2b expression in wild type (A), or following overexpression of spry2 (B), injection of RNA encoding a dn-fgfr (C) or treatment with SU5402 (D). (E,F) Following dn-fgfr injection, the expression of the Bmp target gene ved expands dorsally. (G-J) Inhibition of Fgf signalling reduces or abolishes the expression of dorsal mesodermal markers goosecoid (gsc, G,H) and sonic hedgehog (shh, I,J). (K,L) Conversely, the expression territory of draculin (drl), a marker of the ventral hypoblast, is expanded compared with wild type. (M-P) Compared with wild type (M,O) dn-ras injection causes a severe reduction of the expression domain of the pan-neural marker zic2 (N,P). (Q,R) Two-colour in situ hybridisation with bmp2b (blue) and the anterior neural marker otx2 (green) or (S,T) with ved (blue) and cyp26a (green). Arrowheads (Q-T) indicate the border between the gene expression domains. (A-H) Shield stage, (I-T) 70% epiboly. (A-H) Animal pole views; (I,J,M,N,Q-T) lateral views; (K,L) optical cross-section at the level of the margin; (O,P) dorsal views. (A-N,Q-T) Dorsal towards the right.