Fig. 1. Schematic representation of grafted and scored regions. (A) Lateral (top) and dorsal (bottom) views of the primitive streak showing the regions dissected. The rostral end of the node (RN) was recognised by its wider notochordal plate, and the border (denoted by B) was recognised by the crown (cr) at the caudal end of the node. (B) Schematic diagrams showing the position of the CNH (red dashed lines) in sagittal sections (upper panel; as shown in Fig. 2 and in Fig. S1 in the supplementary material) and transverse sections (lower panel; as shown in Figs 5 and 6). Black dotted lines on the upper panel show the rostrocaudal position of transverse sections. CNH, chordoneural hinge