Expanding Actin Rings Zipper the Mouse Embryo for Blastocyst Formation

Jennifer Zenker, Melanie D. White, Maxime Gasnier, Yanina D. Alvarez, Hui Yi Grace Lim, Stephanie Bissiere, Maté Biro, Nicolas Plachta

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87 Citations (Scopus)


Transformation from morula to blastocyst is a defining event of preimplantation embryo development. During this transition, the embryo must establish a paracellular permeability barrier to enable expansion of the blastocyst cavity. Here, using live imaging of mouse embryos, we reveal an actin-zippering mechanism driving this embryo sealing. Preceding blastocyst stage, a cortical F-actin ring assembles at the apical pole of the embryo's outer cells. The ring structure forms when cortical actin flows encounter a network of polar microtubules that exclude F-actin. Unlike stereotypical actin rings, the actin rings of the mouse embryo are not contractile, but instead, they expand to the cell-cell junctions. Here, they couple to the junctions by recruiting and stabilizing adherens and tight junction components. Coupling of the actin rings triggers localized myosin II accumulation, and it initiates a tension-dependent zippering mechanism along the junctions that is required to seal the embryo for blastocyst formation. Expanding actin rings zipper the mouse embryo to seal it and allow formation of the blastocyst cavity.

Original languageEnglish
Article number29576449
Pages (from-to)776-791
Number of pages16
Issue number3
Publication statusPublished - 19 Apr 2018
Externally publishedYes


  • actin dynamics
  • blastocyst
  • cortical flow
  • epithelia
  • live imaging
  • mammalian development
  • microtubules
  • morphogenesis
  • preimplantation mouse embryo
  • tight junctions

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