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Cite this page: Hill, M.A. (2019, December 13) Embryology Week 2. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Week_2
Self-organization of the human embryo in the absence of maternal tissues
Nat Cell Biol. 2016 May 4. doi: 10.1038/ncb3347. [Epub ahead of print]
Shahbazi MN1, Jedrusik A1, Vuoristo S1, Recher G1, Hupalowska A1, Bolton V2, Fogarty NM3, Campbell A4, Devito LG2, Ilic D2, Khalaf Y2, Niakan KK3, Fishel S4, Zernicka-Goetz M1.
Remodelling of the human embryo at implantation is indispensable for successful pregnancy. Yet it has remained mysterious because of the experimental hurdles that beset the study of this developmental phase. Here, we establish an in vitro system to culture human embryos through implantation stages in the absence of maternal tissues and reveal the key events of early human morphogenesis. These include segregation of the pluripotent embryonic and extra-embryonic lineages, and morphogenetic rearrangements leading to generation of a bilaminar disc, formation of a pro-amniotic cavity within the embryonic lineage, appearance of the prospective yolk sac, and trophoblast differentiation. Using human embryos and human pluripotent stem cells, we show that the reorganization of the embryonic lineage is mediated by cellular polarization leading to cavity formation. Together, our results indicate that the critical remodelling events at this stage of human development are embryo-autonomous, highlighting the remarkable and unanticipated self-organizing properties of human embryos.
Self-organization of the in vitro attached human embryo
Nature. 2016 May 4;533:251-4. doi: 10.1038/nature17948.
Deglincerti A1, Croft GF1, Pietila LN1, Zernicka-Goetz M2, Siggia ED3, Brivanlou AH1.
Implantation of the blastocyst is a developmental milestone in mammalian embryonic development. At this time, a coordinated program of lineage diversification, cell-fate specification, and morphogenetic movements establishes the generation of extra-embryonic tissues and the embryo proper, and determines the conditions for successful pregnancy and gastrulation. Despite its basic and clinical importance, this process remains mysterious in humans. Here we report the use of a novel in vitro system to study the post-implantation development of the human embryo. We unveil the self-organizing abilities and autonomy of in vitro attached human embryos. We find human-specific molecular signatures of early cell lineage, timing, and architecture. Embryos display key landmarks of normal development, including epiblast expansion, lineage segregation, bi-laminar disc formation, amniotic and yolk sac cavitation, and trophoblast diversification. Our findings highlight the species-specificity of these developmental events and provide a new understanding of early human embryonic development beyond the blastocyst stage. In addition, our study establishes a new model system relevant to early human pregnancy loss. Finally, our work will also assist in the rational design of differentiation protocols of human embryonic stem cells to specific cell types for disease modelling and cell replacement therapy.