Loss of Neur causes apical Crb accumulation and slows NB ingression. (A) Live stills from un-injected embryos (control) or sdt dsRNA injected embryos (sdt-RNAi), expressing endo-Sdt::GFP (5 embryos each), GFP::Crb (n = 5 and 8 embryos, respectively) and GFP::CrbRR (n = 8 and 6 embryos, respectively). In the absence of Sdt, GFP::CrbRR remains at the plasma membrane in contrast to GFP::Crb, which is found in endosomes. Scale bar, 10 μm. (B) Ventral views of late stage 8, early stage 9, and mid-stage 9 embryos expressing Dicer-2 maternally and injected with water (control, n = 13) or with neur dsRNA (neur-RNAi, n = 12), stained for Crb and Moesin. Brackets delimit the neuroectoderm. Note ingression of NBs in clusters enriched for apical Crb in neur-RNAi embryos (insets), whereas in controls NBs ingress as individual cells. Ingression ends by early stage 9 (inset, control), whereas apical NB clusters are still visible in neur-RNAi embryos at that stage. Upon division, these supra-numerary NBs disrupt neurectoderm integrity. Anterior is to the left, dorsal is up. Scale bar, 50 μm.