Movie S1

Time-lapse imaging of the dynamic movements of labeled cell clusters in the medial heart primordia (MHP), showing tissue dynamics during heart tube formation. Stripes of cells in the paired MHP were labeled with DiO (green) at three anteroposterior levels. Shown here and in subsequent supplementary movies, are ventral views (embryo's right side is on the left side of each frame; anterior is at the top of each frame), with relative times after the initiation of recording indicated in the upper left corner of each frame. Selected images are shown in Figure 2. Annotated, duplicated time-lapse images are shown in the right panel. Red and blue dots depict the original medial and lateral edges of the labeled cell stripe, respectively.