Fig. 7

Fig. 7 Pou5f1 and EGF Contribute to Control of Blastoderm Cell Migration(A and B) Five minute time series of confocal sections showing deep cell migration in WT (A) and MZspg (B) embryos at 50% epiboly stage. The cell labeled with yellow asterisk slides past neighboring cells, as judged from the position of adherent surfaces (arrowheads). Arrows indicate direction of cell migration. Animal views are shown. Scale bar, 10 μm.(C) Percent change of the adherent surface lengths between 0 and 5 min is significantly higher in WT as compared to MZspg cell clusters (p < 0.001; WT n = 35 focal planes from 12 embryos, MZspg n = 31 focal planes from 11 embryos; error bars show SEM).(D–F′′ ′) Global cell behavior analyzed by 2 hr (sphere to 50% epiboly stage) 3D time-lapse recording of embryos, in which all cell nuclei were labeled by expression of NLS-tomato (confocal stacks 109 μm from the animal pole EVL into the blastoderm). (D–F) Lateral projection views representing a 50 μm sheet transecting the blastoderm perpendicular to the dorsoventral axis were generated and rendered in a 3D image showing the tracks of cell nuclei between 94 and 115 min of the recording. The marked area is shown enlarged at right for time windows as indicated. The plotted lines show tracks of nuclei over 21 min. WT (D) and AG1478-treated WT (E) have longer tracks than MZspg (F). Lateral views, animal pole to the top. Scale bar, 50 μm (D–F).(G–I) Quantification of the average track length, effective net displacement length, and track speed mean are shown (p < 0.01; p < 0.001; n = 6 embryos each; error bars show SEM).(J) A model for the regulatory cascade by which Pou5f1 controls cell behavior during epiboly.See also Figure S5 and Movie S4.