Baz is required for puncta repositioning and SAJ growth. (A–F) Live DE-cad∷GFP. (A–C and E) baz maternal and zygotic mutants shown over cellularization to gastrulation. Arrows indicate apical surface puncta. (D and F) WT controls with equal DE-cad∷GFP transgenes at late cellularization and gastrulation. Arrows indicate apicolateral SAJs. (G and H) WT gastrulation and DE-cad∷GFP/actin∷RFP dual imaging are shown. Arrow indicates SAJ. N, nucleus. (I) Puncta volumes, WT controls versus baz mutants (n = 5 embryos) at gastrulation onset are shown. Insets show example puncta in 3D. (J) Puncta mobility is shown. WT control versus baz mutants are shown at gastrulation onset as 1.5-µm projections. White and yellow arrows show puncta appearance and disappearance, respectively. Boxes indicate regions shown in the kymographs below. (K and L) Later gastrulation is shown. (K) baz mutant cell protrusions and DE-cad∷GFP are shown. (L) baz mutant DE-cad∷GFP in vesicles (arrow) is shown. (M) Model of early AJ assembly in Drosophila. Bars, 5 µm.