WordNet

of or relating to the trophoblast; "trophoblastic cancer"
of or relating to a chorion; "a chorionic villus is a minute vascular projection on the fetal chorion"
the membrane that forms the wall of the blastocyst in early development; aids implantation in the uterine wall; "after implantation of the blastocyst in the uterine wall the trophoblast divides into two layers, the chorion and the placenta"

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/26 21:26:22」(JST)

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Trophoblasts (from Greek trephein: 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 differentiate from the fertilized egg. This layer of trophoblasts is also collectively referred to as "the trophoblast",^[1] or, after gastrulation,^[2] the trophectoderm, as it is then contiguous with the ectoderm of the embryo.

Structure

The trophoblast proliferates and differentiates into 2 cell layers at approximately 6 days after fertilization for humans:

Layer	Location	Description
cytotrophoblast	inner layer	Single celled, inner layer of the trophoblast.
syncytiotrophoblast	outer layer	Thick layer that lacks cell boundaries and grows into the endometrial stroma. It secretes hCG in order to maintain progesterone secretion and sustain a pregnancy.
intermediate trophoblast (IT)	implantation site, chorion, villi (dependent on subtype)	anchor placenta (implanation site IT), unknown (chorionic & villus IT)

Function

Trophoblasts are specialized cells of the placenta that play an important role in embryo implantation and interaction with the decidualised maternal uterus. The core of placental villi contain mesenchymal cells and placental blood vessels that are directly connected to the fetal circulation via the umbilical cord. This core is surrounded by two layers of trophoblast; a single layer of mononuclear cytotrophoblast that fuse together to form the overlying multinucleated syncytiotrophoblast layer that covers the entire surface of the placenta. It is this syncytiotrophoblast that is in direct contact with the maternal blood that reaches the placental surface, and thus facilitates the exchange of nutrients, wastes and gases between the maternal and fetal systems.^{[citation needed]}

In addition, cytotrophoblast in the tips of villi can differentiate into another type of trophoblast called the extravillous trophoblast. Extravillous trophoblast grow out from the placenta and penetrate into the decidualised uterus. This process is essential not only for physically attaching the placenta to the mother, but also for altering the vasculature in the uterus to allow it to provide an adequate blood supply to the growing fetus as pregnancy progresses. Some of these trophoblast even replace the endothelial cells in the uterine spiral arteries as they remodel these vessels into wide bore conduits that are independent of maternal vasoconstriction. This ensures the fetus receives a steady supply of blood, and the placenta is not subjected to fluctuations in oxygen that could cause it damage.^{[citation needed]}

Clinical significance

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 is important in the development of some cases of pre-eclampsia. Too firm an attachment may lead to placenta accreta.

Gestational trophoblastic disease represents a form of proliferation.

Additional images

Blastodermic vesicle of Vespertilio murinus.
Section through embryonic disk of Vespertilio murinus.
Transverse section of a chorionic villus.
Scheme of placental circulation.
The initial stages of human embryogenesis

References

^ http://www.britannica.com/EBchecked/topic/606502/trophoblast
^ Merriam-Webster's Medical Dictionary > trophectoderm Retrieved August 2010

External links

Swiss embryology (from UL, UB, and UF) iperiodembry/carnegie02

UpToDate Contents

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1. 妊娠性絨毛腫瘍：疫学、臨床的特徴、診断、病期分類、およびリスク層別化 gestational trophoblastic neoplasia epidemiology clinical features diagnosis staging and risk stratification
2. 妊娠性絨毛性疾患：病理 gestational trophoblastic disease pathology
3. 抵抗性または再発性の妊娠性絨毛腫瘍のマネージメント management of resistant or recurrent gestational trophoblastic neoplasia
4. 高リスク妊娠性絨毛腫瘍の初期マネージメント initial management of high risk gestational trophoblastic neoplasia
5. 低リスク妊娠性絨毛腫瘍の初期マネージメント initial management of low risk gestational trophoblastic neoplasia

English Journal

PMID 28653360

Bleeding from gestational trophoblastic neoplasia: embolotherapy efficacy and tumour response to chemotherapy.

Wang Z1, Li X1, Pan J1, Chen J1, Shi H1, Zhang X1, Liu W1, Yang N1, Jin Z2, Xiang Y3.
Clinical radiology.Clin Radiol.2017 Nov;72(11):992.e7-992.e11. doi: 10.1016/j.crad.2017.06.004. Epub 2017 Jun 30.
PMID 28673447

Placental Nano-vesicles Target to Specific Organs and Modulate Vascular Tone In Vivo.

Tong M1, Stanley JL2, Chen Q1, James JL1, Stone PR1, Chamley LW1.
Human reproduction (Oxford, England).Hum Reprod.2017 Nov 1;32(11):2188-2198. doi: 10.1093/humrep/dex310.
PMID 29040541

Japanese Journal

症例報告 Quiescent gestational trophoblastic diseaseを疑い経過観察を行った5例

日本婦人科腫瘍学会雑誌 35(2), 210-216, 2017-04
NAID 40021232388

Derivation of Induced Trophoblast Cell Lines in Cattle by Doxycycline-Inducible piggyBac Vectors

PLOS ONE 11(12), 2016-12-01
NAID 120005980901

症例報告臨床的侵入奇胎となり追加治療を要した胎児共存奇胎の2症例 (平成26年度後期学術集会一般演題)

埼玉産科婦人科学会雑誌 = Saitama journal of obstetrics and gynecology 46(2), 184-189, 2016-09
NAID 40021112640

Related Pictures

★リンクテーブル★

リンク元	「chorionic」「絨毛性」「ectoplacental」「trophoderm」
拡張検索	「trophoblastic neoplasm」「gestational trophoblastic neoplasia」「gestational trophoblastic neoplasm」

「chorionic」

Trophoblast
	Blastocyst with an inner cell mass and trophoblast.
Details
Latin	trophoblastus; massa cellularis externa
Days	6
Gives rise to	caul
Identifiers
Gray's	p.46
MeSH	A16.254.085.162
TE	E6.0.1.1.2.0.2
FMA	83029
	Anatomical terminology