Trophoblast
938561
216655107
2008-06-02T16:52:31Z
Winchelsea
4111006
Reverted edits by [[Special:Contributions/64.162.43.75|64.162.43.75]] ([[User talk:64.162.43.75|talk]]) using [[User:MichaelBillington/MWT|MWT]]
{{Infobox Embryology |
Name = {{PAGENAME}} |
Latin = |
GraySubject = 6 |
GrayPage = 46 |
Image = Blastocyst English.svg |
Caption = Blastocyst with an [[inner cell mass]] and [[trophoblast]]. |
Image2 = Gray32.png |
Caption2 = Section through ovum imbedded in the uterine decidua. Semidiagrammatic. <BR><BR>am. [[Amniotic cavity]].<BR>b.c. [[Blood-clot]].<BR>b.s. [[Body-stalk]].<BR>ect. [[Embryonic ectoderm]].<BR>ent. [[Entoderm]].<BR>mes. [[Mesoderm]].<BR>m.v. [[Maternal vessels]].<BR>tr. [[Trophoblast]].<BR>u.e. [[Uterine epithelium]].<BR>u.g. [[Uterine glands]].<BR>y.s. [[Yolk-sac]]. |
System = |
CarnegieStage = |
Days = 6 |
Precursor = |
GivesRiseTo = [[caul]] |
MeshName = Trophoblasts |
MeshNumber = A16.254.085.162 |
DorlandsPre = |
DorlandsSuf = |
}}
'''Trophoblasts''' (from [[Greek language|Greek]] ''threphein'': to feed, and ''blastos'': germinator) are cells forming the outer layer of a [[blastocyst]], which provide nutrients to the [[embryo]] and develop into a large part of the [[placenta]]. They are formed during the first stage of [[pregnancy]] and are the first cells to [[cellular differentiation|differentiate]] from the [[fertilized]] [[ovum|egg]].
==Function==
Trophoblasts are invasive, eroding, and [[metastasizing]] cells of the [[placenta]].
Trophoblasts mediate the implantation of the embryo into the [[endometrium]], but they are never incorporated into the mother's body or the [[fetus]]. They are not "fetal" cells.
Trophoblasts become inert during pregnancy and are completely rejected by the fetus and mother at delivery. They can be seen as the thin membrane covering the fetus at birth, the [[caul]].<ref>[http://www.cancure.org/trophoblastic_nature_of_cancer.htm The Trophoblastic Nature of Cancer and Pregnancy Cycle as the Basis for the Enzyme Treatment of Cancer]</ref>
==Differentiation==
The trophoblast proliferates and differentiates into 2 cell layers:
{| class="wikitable"
| '''Layer''' || '''Location''' || '''Description'''
|-
| [[cytotrophoblast]] || inner layer || Single celled layer adjacent to trophoblast.
|-
| [[syncytiotrophoblast]]|| outer layer || Thick layer that lacks cell boundaries and grows into the [[endometrial]] [[stroma]]. It secretes [[Human chorionic gonadotropin|hCG]] in order to maintain [[progesterone]] secretion and sustain a pregnancy.
|}
==Pathology==
The invasion of a specific type of trophoblast (extravillous trophoblast) into the maternal [[uterus]] is a vital stage in the establishment of [[pregnancy]]:
* Failure of the trophoblast to invade sufficiently may be important in the development of some cases of [[pre-eclampsia]].
* Too firm an attachment may lead to [[placenta accreta]].
==Additional images==
<gallery>
Image:Gray10.png|Blastodermic vesicle of Vespertilio murinus.
Image:Gray11.png|Section through embryonic disk of Vespertilio murinus.
Image:Gray35.png|Transverse section of a chorionic villus.
Image:Gray39.png|Scheme of placental circulation.
</gallery>
==See also==
* [[Syncytiotrophoblast]]
* [[Hydatidiform mole]]
==References==
<references/>
==External links==
* {{EmbryologySwiss|iperiodembry/carnegie02}}
* [http://www.ansi.okstate.edu/course/3443/study/EmbryoDevelopment/porcine/sld020.htm Oklahoma State]
* [http://soma.npa.uiuc.edu/labs/greenough/statements/rswain/hormones/images/blastocyst.gif University of Illinois]
* [http://www-personal.umich.edu/~bradbuck/index_files/image004.jpg Diagram at umich.edu]
{{Embryology}}
[[Category:Developmental biology]]
[[cs:Trofoblast]]
[[de:Trophoblast]]
[[es:Trofoblasto]]
[[pl:Trofoblast]]
[[pt:Trofoblasto]]