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Fig. 3. Expression of organiser genes is initiated on the ventral side when BMP signals are ectopically blocked, but is not maintained by the late gastrula stage. (A,E,I,M,Q,U) Vegetal view of uninjected mid-gastrulae (stage 11). (B,F,J,N,R,V) Vegetal view of mid-gastrulae injected ventrally with tBR RNA and lacZ RNA as lineage tracer. (C,G,K,O,S,W) Dorsal-vegetal view of uninjected late gastrulae (stage 13). (D,H,L,P,T,X) Dorsal-vegetal view of late gastrulae injected ventrally with tBR RNA. The identity of the probes used is indicated on the left of each row of panels. Note that the expression of all the genes tested is lost at the late gastrula stage, with the exception of chordin (D). β-galactosidase activity is shown in red, gene expression in purple. |
