- Inner cell mass
Infobox Embryology
Name = PAGENAME
Latin =
GraySubject = 6
GrayPage = 46
Caption = Blastocyst with aninner cell mass andtrophoblast .
Caption2 =
System =
CarnegieStage = 3
Days = 6
Precursor =blastocyst
GivesRiseTo =epiblast ,hypoblast
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MeshNumber =
DorlandsPre = m_04
DorlandsSuf = 12515766
In earlyembryogenesis of mosteutherian mammals, the inner cell mass (abbreviated ICM and also known as the embryoblast orpluriblast (the latter term being applicable to all mammals)) is the mass of cells inside the primordial embryo that will eventually give rise to the definitive structures of the fetus. This structure forms in the earliest steps of development, beforeimplantation into theendometrium of theuterus has occurred. The ICM lies within theblastocoele (more correctly termed "blastocyst cavity", as it is not strictly homologous to the blastocoele of anamniote vertebrates) and is entirely surrounded by the single layer of cells calledtrophoblast .Further development
The ICM differentiates into two types of cells,
epiblast andhypoblast .Only the cells of the epiblast give rise to cells inside the embryo, while hypoblast cells form only extraembryonic tissue (
extraembryonic endoderm ). All threegerm layers of the definitive embryo, as well asextraembryonic mesoderm , arise from theepiblast .tem cells
It is the source of early
stem cell s. [cite web |url=http://www.kumc.edu/stemcell/early.html |title=Stem Cell Research Basics: Early Stem Cells |accessdate=2007-10-11 |format= |work=]It can form all tissues except
trophoblast . [cite web |url=http://cancerweb.ncl.ac.uk/cgi-bin/omd?inner+cell+mass |title=Definition: inner cell mass from Online Medical Dictionary |accessdate=2007-10-11 |format= |work=]
=AdditionalReferences
External links
* http://isc.temple.edu/marino/embryology/lecture1-3.htm
* http://isc.temple.edu/marino/embryology/EMBI97/img010.GIF
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