A method to image the EMT in zebrafish tailbuds at high resolution is established.
Wild-type cells use productive lamellipodia to migrate persistently anteriorly.
Cells lacking Tbx16 and Msgn1 are motile but cannot leave the tailbud.
These mutant cells do not migrate directionally or form productive lamellipodia.
Embryos have a directional migratory cue that is independent of Tbx16 and Msgn1.