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 2

Polarity in the mouse preimplantation embryo.

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Polarity in the mouse preimplantation embryo. (A) At the eight-cell stag...
(A) At the eight-cell stage, all blastomeres polarize along the axis of cell contact, forming outward, apical domains and inward-facing basolateral domains. (B) As the embryo grows from eight to 16 cells, blastomeres that divide parallel to the inside-outside axis produce two outside, polar cells. Blastomeres that divide perpendicular to the inside-outside axis produce one outside, polar daughter cell and one non-polar, inside daughter cell. This creates two populations of cells: outside, polar cells and inside, nonpolar cells. These two types of cell division also occur as the embryo grows from 16 to 32 cells.