Dynamin is required for the loss of the apical domain during NB ingression. (A) Stills from time-lapse movies of ingressing NBs of Dyn^TS (shi^ts1 mutants) at 22 and 32°C, expressing ubi-Ecad::GFP. Dividing ventral midline cells (VMC) are pseudo-colored in blue. Note ingression of medial NBs (yellow circles) adjacent to the VMC at the permissive temperature of 22°C. Ingression is stalled upon Dynamin inhibition at the restrictive temperature of 32°C and ectopic Ecad accumulation is seen at cell–cell contacts throughout the germband No NBs with constricted apical domains are apparent. T = 0 min indicates onset of stage 8. Scale bar, 10 μm. (B) Stills from time-lapse movies of ingressing NBs of Dyn^TS at 22°C (permissive temperature; 32 NBs, three embryos) and 32°C (restrictive temperature; 41 NBs, two embryos) expressing endo-Crb::GFP. Dynamin blockage at the restrictive temperature beginning at mid-stage 8 (3 h 30 min AEL) led to incomplete ingression in 56% of NBs and 22% of NBs divided on the embryo surface (normal divisions occur after NB complete ingression and are located below the ectoderm). Note higher accumulation of Crb on the apical surface of the delayed cells at 32°C compared to controls at 22°C (quantifications shown in Fig. 4 C). Scale bar, 2.5 μm.