Fig. 9. Asymmetric radial intercalation and cell shape changes of the epiblast layer drive epibolic expansion of the lateral and ventral blastoderm of the zebrafish. Cells of the interior layer of the epiblast (blue, light blue, white) sequentially intercalate between the cells of the exterior layer (light green) and then flatten; arrows indicate directions of cell movement. Hypoblast cells (red) and EVL cells (dark green) move independently of the epiblast. ee, exterior layer of the epiblast; hb, hypoblast layer; ie, interior layer of the epiblast; YSL, yolk syncytial layer.