Editing Embryoid body (section)

==Differentiation within EBs==
Within the context of ESC [[cellular differentiation|differentiation]] protocols, EB formation is often used as a method for initiating spontaneous differentiation toward the three [[germ layer|germ lineages]].  EB differentiation begins with the specification of the exterior cells toward the primitive endoderm phenotype.<ref>{{Cite journal 
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| title = Fibroblast growth factor (FGF) signaling through PI 3-kinase and Akt/PKB is required for embryoid body differentiation 
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| journal = Oncogene 
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}}</ref>  The cells at the exterior then deposit [[extracellular matrix]] (ECM), containing [[collagen type IV|collagen IV]] and [[laminin]],<ref>{{Cite journal 
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| title = Monoclonal antibodies to laminin reveal the heterogeneity of basement membranes in the developing and adult mouse tissues 
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| title = Fibroblast growth factor signaling and basement membrane assembly are connected during epithelial morphogenesis of the embryoid body 
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| volume = 153 
| issue = 4 
| pages = 811–822 
| year = 2001 
| pmid = 11352941 
| pmc = 2192393 | doi=10.1083/jcb.153.4.811
}}</ref> similar to the composition and structure of [[basement membrane]].  In response to the ECM deposition, EBs often form a cystic cavity, whereby the cells in contact with the basement membrane remain viable and those at the interior undergo apoptosis, resulting in a fluid-filled cavity surrounded by cells.<ref>{{Cite journal 
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| title = Signals for death and survival: A two-step mechanism for cavitation in the vertebrate embryo 
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| title = Absence of basement membranes after targeting the LAMC1 gene results in embryonic lethality due to failure of endoderm differentiation 
| journal = The Journal of Cell Biology 
| volume = 144 
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| pmc = 2148127 | doi=10.1083/jcb.144.1.151
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| title = Regulation of programmed cell death by basement membranes in embryonic development 
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| year = 2000 
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}}</ref>  Subsequent differentiation proceeds to form derivatives of the three germ lineages.  In the absence of supplements, the “default” differentiation of ESCs is largely toward ectoderm, and subsequent [[neural crest|neural lineages]].<ref>{{Cite book 
| last1 = Ying | first1 = Q. L. 
| last2 = Smith | first2 = A. G. 
| chapter = Defined Conditions for Neural Commitment and Differentiation 
| title = Differentiation of Embryonic Stem Cells 
| series = Methods in Enzymology 
| volume = 365 
| pages = 327–341 
| year = 2003 
| pmid = 14696356
 | doi=10.1016/s0076-6879(03)65023-8
| isbn = 9780121822682 
}}</ref>  However, alternative media compositions, including the use of [[fetal bovine serum]] as well as defined growth factor additives, have been developed to promote the differentiation toward [[mesoderm]] and [[endoderm]] lineages.<ref>{{Cite journal 
| last1 = Wiles | first1 = M. V. 
| last2 = Keller | first2 = G. 
| title = Multiple hematopoietic lineages develop from embryonic stem (ES) cells in culture 
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| pages = 259–267 
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| doi = 10.1016/j.exphem.2008.04.003 
| title = Analysis of the temporal and concentration-dependent effects of BMP-4, VEGF, and TPO on development of embryonic stem cell–derived mesoderm and blood progenitors in a defined, serum-free media 
| journal = Experimental Hematology 
| volume = 36 
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| pmid = 18550259 
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| title = Wnt, Activin, and BMP Signaling Regulate Distinct Stages in the Developmental Pathway from Embryonic Stem Cells to Blood 
| doi = 10.1016/j.stem.2007.10.011 
| journal = Cell Stem Cell 
| volume = 2 
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| pages = 60–71 
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| pmid = 18371422 
| pmc =2533280 
}}</ref>

As a result of the three-dimensional EB structure, complex morphogenesis occurs during EB differentiation, including the appearance of both epithelial- and mesenchymal-like cell populations, as well as the appearance of markers associated with the [[epithelial-mesenchymal transition]] (EMT).<ref name="ReferenceH">{{Cite journal 
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| doi = 10.1016/j.stem.2008.09.013 
| title = Wnt Signaling Mediates Self-Organization and Axis Formation in Embryoid Bodies 
| journal = Cell Stem Cell 
| volume = 3 
| issue = 5 
| pages = 508–518 
| year = 2008 
| pmid = 18983966 
| pmc =2683270 
}}</ref><ref>{{Cite journal 
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| last8 = McDevitt | first8 = T. C. 
| doi = 10.1369/jhc.2009.954826 
| title = Synthesis and Organization of Hyaluronan and Versican by Embryonic Stem Cells Undergoing Embryoid Body Differentiation 
| journal = Journal of Histochemistry and Cytochemistry 
| volume = 58 
| issue = 4 
| pages = 345–358 
| year = 2009 
| pmid = 20026669 
| pmc =2842597 
}}</ref>  Additionally, the inductive effects resulting from signaling between cell populations in EBs results in spatially and temporally defined changes, which promote complex [[morphogenesis]].<ref>{{Cite journal 
| last1 = Bauwens | first1 = C. L. 
| last2 = Song | first2 = H. 
| last3 = Thavandiran | first3 = N. 
| last4 = Ungrin | first4 = M. 
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| s2cid = 22010083 
| doi = 10.1089/ten.TEA.2010.0563 
| title = Geometric Control of Cardiomyogenic Induction in Human Pluripotent Stem Cells 
| journal = Tissue Engineering Part A 
| volume = 17 
| issue = 15–16 
| pages = 1901–1909 
| year = 2011 
| pmid = 21417693 
| pmc = 
| hdl = 1807/33799 
| hdl-access = free 
}}</ref> Tissue-like structures are often exhibited within EBs, including the appearance of blood islands reminiscent of early blood vessel structures in the developing embryo, as well as the patterning of [[neurite]] extensions (indicative of neuron organization) and spontaneous contractile activity (indicative of [[cardiomyocyte]] differentiation) when EBs are plated onto adhesive substrates such as [[gelatin]].<ref name="ReferenceA"/>  More recently, complex structures, including optic cup-like structures were created in vitro resulting from EB differentiation.<ref>{{Cite journal 
| last1 = Eiraku | first1 = M. 
| last2 = Takata | first2 = N. 
| last3 = Ishibashi | first3 = H. 
| last4 = Kawada | first4 = M. 
| last5 = Sakakura | first5 = E. 
| last6 = Okuda | first6 = S. 
| last7 = Sekiguchi | first7 = K. 
| last8 = Adachi | first8 = T. 
| last9 = Sasai | first9 = Y. 
| doi = 10.1038/nature09941 
| title = Self-organizing optic-cup morphogenesis in three-dimensional culture 
| journal = Nature 
| volume = 472 
| issue = 7341 
| pages = 51–56 
| year = 2011 
| pmid = 21475194 
| pmc = 
| bibcode = 2011Natur.472...51E 
| s2cid = 4421136 
}}</ref>