Page 126 - ESHRE2019

How are cells positioned internally or externally? ‐ The classical theory ‐
External allocation
Internal allocation
Outer cell contribute to the trophectoderm, while inner cell contribute to the inner cell mass
Both cell remain external and contribute
to the trophectoderm
How are cells positioned internally or externally?
‐ New findings: cortical tension drives inner cell allocation ‐
Key points of the new model
• Myosin II accumulates around constricting cells and is needed for their allocation
• Subcellular heterogeneities in tensile forces occur in adjacent cells
• Apical constriction allocates the first inner cells of the mouse
embryo
Samarage et al., 2015
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