Editing Gastrulation (section)

{{Short description|Embryologic stage in which germ layers form}}
{{Infobox embryology
| Name     = Gastrulation
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| Image    = Blastula.png
| Caption  = Gastrulation occurs when a [[blastula]], made up of one layer, folds inward and enlarges to create a gastrula. This diagram is color-coded: [[ectoderm]], blue; [[endoderm]], green; [[blastocoel]] (the yolk sac), yellow; and [[archenteron]] (the primary gut), purple.
| Image2   =
| Caption2 =
}}

'''Gastrulation''' is the stage in the early [[embryonic development]] of most [[animals]], during which the [[blastula]] (a single-layered hollow sphere of [[Cell (biology)|cell]]s), or in mammals, the [[blastocyst]], is reorganized into a two-layered or three-layered embryo known as the '''gastrula'''.<ref>{{Cite book |last=Urry |first=Lisa |title=Campbell Biology |publisher=Pearson |year=2016 |isbn=978-0134093413 |edition=11th |pages=1047}}</ref> Before gastrulation, the [[embryo]] is a continuous [[Epithelium|epithelial]] sheet of cells; by the end of gastrulation, the embryo has begun [[Cellular differentiation|differentiation]] to establish distinct [[cell lineage]]s, set up the basic axes of the body (e.g. [[Anatomical terms of location#Dorsal and ventral|dorsal–ventral]], [[Anatomical terms of location#Anterior and posterior|anterior–posterior]]), and internalized one or more cell types, including the prospective [[Gastrointestinal tract|gut]].<ref name="Gilbert-2016">{{Cite book|last=Gilbert|first=Scott F. |title=Developmental biology|date=2016|author2=Michael J. F. Barresi|isbn=978-1-60535-470-5|edition=Eleventh |location=Sunderland, Massachusetts |publisher=Sinauer |oclc=945169933}}</ref>