Making the blastocyst: lessons from the mouse
Katie Cockburn, Janet Rossant
Katie Cockburn, Janet Rossant
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Making the blastocyst: lessons from the mouse

Abstract

Mammalian preimplantation development, which is the period extending from fertilization to implantation, results in the formation of a blastocyst with three distinct cell lineages. Only one of these lineages, the epiblast, contributes to the embryo itself, while the other two lineages, the trophectoderm and the primitive endoderm, become extra-embryonic tissues. Significant gains have been made in our understanding of the major events of mouse preimplantation development, and recent discoveries have shed new light on the establishment of the three blastocyst lineages. What is less clear, however, is how closely human preimplantation development mimics that in the mouse. A greater understanding of the similarities and differences between mouse and human preimplantation development has implications for improving assisted reproductive technologies and for deriving human embryonic stem cells.

Authors

Katie Cockburn, Janet Rossant

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Figure 4

Models of EPI/PE segregation in the mouse embryo.

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Models of EPI/PE segregation in the mouse embryo. (A) In the position-de...
(A) In the position-dependent model, the mouse ICM at E3.5 is composed of a uniform population of bipotential cells, and those cells located on the outside surface of the ICM become PE due to some form of positional information. (B) In the Fgf/MAPK-dependent model, cells of the ICM are initially bipotential, but differences in Fgf signaling cause them to become either Nanog- or Gata6-positive by E3.5. These cells are distributed randomly in the ICM, and cell sorting combined with apoptosis results in the formation of organized PE and EPI layers by E4.5.