Fig. 5. Inner cells can move over outer cells. A time-lapse series of a Drosophila embryo showing inner cells (those not adjacent to the ectoderm) moving over outer cells (see Movie 3 in the supplementary material). (A) A 2 µm z-series at 0:31:00 showing a labelled cell (white dot and arrow) that is, at this time, the most laterally placed cell. (B) A reconstructed cross-sectional time-series in which the labelled cell (white dot and arrows) is overtaken by inner cells (arrowheads). (C) A z-series at end of the time-lapse showing that at deeper z-slices new cells (arrowhead) are now more dorsolaterally placed than the labelled cell (arrow). Scale bar: 20 µm.