Figure 6: Quantification of endoderm cell dynamics reveals conserved flow patterns.

For quantitative analysis, movies were split into early (60–75% epiboly) and late gastrulation (75% epiboly, tail bud). (a–d) Orientation of cell migration (a,c) for wild type and (b,d) for cxcr4a morphants calculated on the angle-preserving Mercator projection (Supplementary Movies 11 and 13). Cell tracks from single embryos are shown on the top, the overlay of cell tracks from 12 embryos below. The colour scale indicates the unsigned angle between the cell track and the dorsal midline, direction of cell movement is indicated by white arrows in a. (e,f) Streamlines obtained from the cell tracks of multiple wild-type and cxcr4a morphant embryos to depict the overall flow pattern of endoderm cells during gastrulation. (g) Overlay of streamlines of wild type (blue) and cxcr4a morphants (red, n=12 each). Maps from different embryos were registered with the position of DFCs at tailbud stage for the overlay. (h–k) Spatial distribution of cells as kernel-density estimate on the area-preserving Bonne projections (h,j) for wild type and (i,k) for cxcr4a morphants (Supplementary Movie 14). Cell densities from single embryos are shown on the top, the averaged density distribution from 12 embryos below. The colour scale indicates local cell density from 0 to >8 cells/1,000 μm². (l) The distance between DFCs and the approaching endoderm margin during the course of gastrulation, obtained by calculating the 0.1 quantile of the cellular distributions in wild type (n=12, blue) and cxcr4a morphant (n=12, red) (Supplementary Fig. S8). The line graph represents the mean distance and the shaded region the standard deviation. In all images the equator corresponds to the dorsal midline, anterior to the left.