Editing Mesoderm (section)

{{Short description|Middle germ layer of embryonic development}}
{{More citations needed|date=May 2022}}
{{Infobox embryology
| Name          = Mesoderm
| Latin         =
| Image         = Embryonic origin of mesoderm.png
| Caption       = Tissues derived from mesoderm.
| Image2        = Gray21.png
| Caption2      = Section through a human embryo
| System        =
| CarnegieStage =
| Days          = 16
| Precursor     =
| GivesRiseTo   =
}}

The '''mesoderm''' is the middle layer of the three [[germ layer]]s that develops during [[gastrulation]] in the very early [[embryonic development|development of the embryo]] of most animals. The outer layer is the [[ectoderm]], and the inner layer is the [[endoderm]].<ref name="RFB2004Mesoderm" /><ref name="Langman's Medical Embryology 2010">Langman's Medical Embryology, 11th edition. 2010.</ref>

The mesoderm forms [[mesenchyme]], [[mesothelium]] and [[coelomocyte]]s. Mesothelium lines [[coelom]]s. Mesoderm forms the muscles in a process known as [[myogenesis]], septa (cross-wise partitions) and [[Mesentery (zoology)|mesenteries]] (length-wise partitions); and forms part of the [[gonad]]s (the rest being the [[gamete]]s).<ref name="RFB2004Mesoderm">{{Cite book |last=Ruppert |first=E.E. |url=https://archive.org/details/isbn_9780030259821/page/217 |title=Invertebrate Zoology |last2=Fox |first2=R.S. |last3=Barnes |first3=R.D. |publisher=Brooks/Cole |year=2004 |isbn=978-0-03-025982-1 |edition=7th |pages=[https://archive.org/details/isbn_9780030259821/page/217 217–218] |chapter=Introduction to Bilateria |url-access=registration}}</ref>{{Unreliable source?|date=June 2011}} Myogenesis is specifically a function of [[Mesenchymal Stem Cell|mesenchyme]].

The mesoderm differentiates from the rest of the embryo through [[intercellular signaling]], after which the mesoderm is [[Cell polarity|polarized]] by an [[FGF and mesoderm formation|organizing center]].<ref name="Kimelman-2004-p363">{{Cite book |last=Kimelman, D. |url=https://archive.org/details/gastrulationfrom0000unse |title=Gastrulation: from cells to embryo |last2=Bjornson, C. |publisher=CSHL Press |year=2004 |isbn=978-0-87969-707-5 |editor-last=Stern, Claudio D. |page=363 |chapter=Vertebrate Mesoderm Induction: From Frogs to Mice |chapter-url=https://books.google.com/books?id=ljAKtC-iIrIC&pg=PA363 |url-access=registration |name-list-style=amp}}</ref> The position of the organizing center is in turn determined by the regions in which [[beta-catenin]] is protected from degradation by GSK-3. Beta-catenin acts as a co-factor that alters the activity of the transcription factor tcf-3 from repressing to activating, which initiates the synthesis of gene products critical for mesoderm differentiation and gastrulation.  Furthermore, mesoderm has the capability to induce the growth of other structures, such as the [[neural plate]], the precursor to the nervous system.