Fig. 7. Reconstruction of cell movement and shape change during notochord formation in a living Corella inflata embryo (the same shown in Fig. 6). Cell outlines represent approximate cell boundaries as seen in cross section near the dorsal surface (left column) or ventral surface (right column) of the notochord plate. Anterior is to the left in all panels. Times shown are from completion of the final primary division. Blue cells remained within the dorsal plate; Grey cells started within or intercalated into the ventral folds. Cells 1-31 derive from the primary lineage. Cells B1-B8 derive from the secondary lineage. Cell 26 failed to divide for the last time but nevertheless changed shape and intercalated as other cells do. In the lowermost panels, part of the notochord has extended rightward out of the video camera’s field of view.
