Cortical Tension Drives Pluripotent Inner Mass Formation in the Mammalian Embryo

WHITE MD; ALVAREZ, YANINA; SAMARAGE CR; PLACHTA N

Workshop; European Molecular Biology Organization Workshop ? Molecular mechanisms of developmental and regenerative biology; 2018

Every cell in our body originates from the pluripotent inner mass of theembryo, yet the mechanical forces forming this structure are unknown. Wedeveloped new quantitative imaging technologies to track changes in cell shapeand position in living mouse embryos. We characterized the main morphogeneticmechanisms forming the pluripotent inner mass and showed how mechanical forcesacting within the embryo control cell-positioning events.  Using hightemporal resolution live imaging we show that the apical domain, previouslyproposed to determine lineage segregation, is disassembled before celldivision. Instead, we find that anisotropies in cortical tension play a keyrole in determining which cells undergo internalization to form the inner mass.We characterize the underlying mechanisms and explain how the directionality oftensile forces coordinates cell rearrangements during early mammaliandevelopment.