| 11. | It is derived from the epiblast layer, which lies between the hypoblast layer and the amnion.
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| 12. | Within birds and mammals, epiblast cells converge at the midline and ingress at the primitive streak.
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| 13. | The epiblast is surrounded by the visceral endoderm, the equivalent of the hypoblast of humans and chicks.
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| 14. | Multiple processes control cell lineage specification in the blastocyst to produce the trophoblast, epiblast, and primitive endoderm.
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| 15. | During approximately the same time, WNT3 starts to be expressed in the posterior visceral endoderm of the epiblast.
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| 16. | PGCs come from the epiblast and move to the hypoblast to form the germinal crescent ( anterior extraembryonic structure ).
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| 17. | Primary mesenchyme is the first embryonic mesenchymal tissue to emerge, and it is produced from EMT in epiblast cells.
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| 18. | This bilaminar blastocyst also defines the primitive dorsal ventral axis . the epiblast is dorsal and the hypoblast is ventral.
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| 19. | PGCs come from the epiblast and migrate subsequently into the mesoderm, the endoderm and the posterior of the yolk sac.
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| 20. | Soon amniogenic ( amnion forming cells ) amnioblasts separate from the epiblast and line the amnion, which encloses the amniotic cavity.
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