Fig. 3. Details of migrating AVE cells, showing filopodial processes. In all the panels, proximal is to the top and distal to the bottom. (A,B) Cells from one embryo, separated by an interval of 10 minutes. (C,D) Cells from a different embryo, separated by an interval of 12 minutes. Filopodia (marked with arrows) form primarily in the proximal direction (the direction of motion of the cells). (E,F) Panels separated by an interval of 10 minutes showing an AVE cell dividing (arrowhead). The orientation of the division of AVE cells is not consistently aligned to the direction of motion of the AVE, and divisions are not observed frequently enough to drive the movement of the AVE. Scale bar in A: 10 µm for A-F. (G) A polar plot of the direction and length of 23 filopodia observed in seven embryos. The lengths of the filopodia are expressed as a fraction of the radius of the cell. Filopodia form predominantly in the proximal direction of the embryo and are often greater than one cell radius in length.