Movie S1.

Ingression of fluorescent endodermal cells in the aggregate. Time-lapse recording of the aggregate made of wild-type ectoderm and lifeact-mOrange2–expressing endoderm. Maximum projection of the 110-μm deep Z-stacks taken each 4 min starting at 1 hpd. The first 180 Z-stacks are shown. Most endodermal cells ingress and disappear from the surface of the aggregate by 4.5 hpd.