English: Supplementary Movie 8 Selected cells including eight progenitors of the primary notochord are highlighted with colored dots at the onset of gastrulation. One cell (in yellow) is kept at a fixed position throughout the movie. Color code is propagated along the tracking to reveal the cells' clonal history and displacement in space and time. A single orthoslice of the raw data (in gray levels) is automatically adjusted to follow the selected yellow cell. The other cells do not necessarily remain in the same plane, but are accurately tracked. The whole dataset was validated and corrected to become a gold standard (Mov-IT visualization tool).