Fig. 1.

Concerted cell divisions occur during AVE migration (A) Schematic view of the experimental design: double transgenic R26Fucci2a/CerI-GFP E5.5 embryos were recovered and live imaged. The R26Fucci2a cell cycle reporter was used to identify cells in S/G2/M phase (labelled with mVenus-hGem(301/120) and termed mVenus⁺ cells) and AVE migration was evaluated as distance between leading CerI-GFP⁺ cell and distal tip of the embryo over time. (B) Anterior and posterior view (upper and middle panels) of R26Fucci2a (mVenus signal is shown as multi-coloured LUT Fire) in VE and migrating AVE cells (bottom panel). Extra-Embryonic/Embryonic boundary is shown as dotted line. (C) mVenus⁺ cells in total (upper panel), anterior (middle panel) and posterior (bottom panel) embryonic VE. Number of cells are shown in individual embryos (thin coloured lines) or as mean (thick black line). For comparing all the embryos (raw values are shown in Figs. S1C–E) we considered time 0 h as the time point before the peak (1 h) of mVenus⁺ cells shown in total emVE (bottom panel). (D) Decrease of mVenus⁺ cells per h in the anterior or posterior emVE during time interval 1 h–5 h. Data are shown as mean ± sem (Unpaired t-test, *p = 0.03). (E) AVE migration shown as distance between leading CerI-GFP⁺ cell and distal tip of the embryo over time (1 h time interval). Values are shown in individual embryos (thin coloured lines) or as mean (thick black line). For comparing all the embryos (raw values are shown in Fig. S1F) we considered time 0 h as the time point before the peak (1 h) of mVenus⁺ cells shown in total emVE. (F) AVE migration speed shown as μm/h before and after the peak of mVenus⁺ cells. Data are shown as mean ± sem (Unpaired t-test, *p = 0.03).