Fig. 1.

ESCs display strong size asymmetries at cell division. (A) Representative time-lapse images of colonies of naïve ESCs expressing H2B–RFP (red) and labeled with CellMask™ Deep Red (cyan) with a cell dividing inside the colony (top) and a cell dividing at the periphery of the colony (bottom). A single Z-plane is shown. Scale bars: 10 µm. Cell boundaries are highlighted with yellow dotted line. Images on the right illustrate segmented 3D cell shapes. (B) Dot plot representing the size asymmetry ratio measured in 3D between daughter cells for single ESCs (‘isolated’, light gray), ESCs dividing inside of a colony (‘inside’, medium gray) and ESCs dividing at the periphery of a colony with the mitotic spindle oriented parallel (‘orthoradial’, orange) or perpendicular (‘radial’, red) to the colony border. The mean±s.d. (N=4) are shown. Datapoints corresponding to isolated ESCs were replotted from Chaigne et al. (2020), data for cells dividing in colonies were obtained by re-analyzing videos acquired for Chaigne et al. (2020). (C) Example plots showing the evolution of the volumes of daughter cells after cell division at the periphery of the colony, in cases where the outside cell is the bigger one (top) or the smaller one (bottom). 0 is the time of cytokinesis. The time when the size asymmetry reported in D is measured (15 min) is highlighted with a dashed line. (D) Dot plot showing the size asymmetry ratio between daughter cells for cells dividing at the periphery of the colony, with the outside-positioned daughter cell being the bigger one (left) or the smaller one (right). The mean±s.d. are shown (N=3). P-values were calculated with a Mann–Whitney test.