Movie 5.

Laser ablation of the flanking, non-constricting cells delays the transition from apical constriction to invagination. Laser ablation of two strips of flanking cells adjacent to the constriction domain in wildtype embryos during apical constriction. A stage matched, non-ablated embryo is shown on the left for comparison. Top: cross-section view; Bottom: ventral surface view. Cell membranes are visualized using E-cadherin-GFP. T = 00:00 (mm:ss) corresponds to the transition from apical constriction to invagination in control embryos.