関: trophectodermal、trophoectoderm

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/17 00:09:58」(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. 異数性診断のための着床前遺伝子スクリーニング（PGS） preimplantation genetic screening pgs for aneuploidy
2. 着床前遺伝子診断 preimplantation genetic diagnosis
3. 着床前の男女生み分け技術 techniques for preimplantation sex selection
4. 胎盤の発達および生理学 placental development and physiology
5. 母体 - 胎児接点の免疫 immunology of the maternal fetal interface

English Journal

Mapping global changes in nuclear cytosine base modifications in the early mouse embryo.

Li Y1, Seah MK1, O'Neill C2.
Reproduction (Cambridge, England).Reproduction.2016 Feb;151(2):83-95. doi: 10.1530/REP-15-0207.
Reprogramming epigenetic modifications to cytosine is required for normal embryo development. We used improved immunolocalization techniques to simultaneously map global changes in the levels of 5'-methylcytosine (5meC) and 5'-hydroxymethylcytosine (5hmC) in each cell of the embryo from fertilizatio
PMID 26660107

Cryotop vitrification of porcine parthenogenetic embryos at the early developmental stages.

Wu GQ1, Quan GB1, Shao QY1, Lv CR1, Jiang YT1, Zhao ZY1, Hong QH2.
Theriogenology.Theriogenology.2016 Feb;85(3):434-40. doi: 10.1016/j.theriogenology.2015.09.015. Epub 2015 Sep 12.
The objective of this study was to evaluate the effects of early developmental stages at which Cryotop vitrification is performed on subsequent survival and in vitro development of porcine parthenogenetic activation embryos. The zygotes that were cultured for 4, 8, and 18 hours post electric activ
PMID 26462660

Epidermal growth factor: Porcine uterine luminal epithelial cell migratory signal during the peri-implantation period of pregnancy.

Jeong W1, Jung S1, Bazer FW2, Song G3, Kim J4.
Molecular and cellular endocrinology.Mol Cell Endocrinol.2016 Jan 15;420:66-74. doi: 10.1016/j.mce.2015.11.023. Epub 2015 Nov 24.
The majority of early conceptus mortality in pregnancy occurs during the peri-implantation period, suggesting that this period is important for conceptus viability and the establishment of pregnancy. Successful establishment of pregnancy in all mammalian species depends on the orchestrated molecular
PMID 26620571

Japanese Journal

Preferential emergence of cell types expressing markers for primitive endoderm lineages in mouse embryonic stem cells expressing exogenous EGAM1 homeoprotein(CELL AND TISSUE ENGINEERING)

Soma Miki,Iha Momoe,Kihara Yumi,Sato Shiori,Sato Yuki,Sato Sho,Mori Yuki,Sugawara Saiko,Kasuga Kano,Kojima Ikuo,Kobayashi Masayuki
Journal of bioscience and bioengineering 114(3), 342-346, 2012-09
… On the other hand, Egam1 transfectants inhibited the expression of specific genes for the embryonic lineages, including Fgt5 (epiblast) and T (mesoderm), in addition to Cdx2, a specific gene for the extra-embryonic trophectoderm lineages. … Taken together, the results obtained in this study suggested that mouse ES cells expressing exogenous EGAM1 preferentially differentiate into extra-embryonic primitive endoderm lineages, rather than embryonic lineages or extra-embryonic trophectoderm lineages. …
NAID 110009517388

TEMPORAL EXPRESSION OF FUNCTIONAL LOW DENSITY LIPOPROTEIN RECEPTORS AND CATALYTIC ENZYMES IN STEROID HORMONE SYNTHESIS OF MOUSE PREIMPLANTATION EMBRYOS

Sato Naoki,Terada Yukihiro
秋田医学 39(1), 1-12, 2012-09
… The expression of LDLR protein was detected in trophectoderm cells of blastocysts, whereas P450scc was detected in cytoplasm of oocytes and all embryos. …
NAID 110009468860

Altered Gene Expression Profiles in Mouse Tetraploid Blastocysts

PARK Mi-Ryung,HWANG Kyu-Chan,BUI Hong-Thuy,CHO Ssang-Goo,PARK Chankyu,SONG Hyuk,OH Jae-Wook,KIM Jin-Hoi
The Journal of reproduction and development 58(3), 344-352, 2012-06-01
… In contrast, trophectoderm-related gene transcripts showed an approximately 10 to 40% increase. …
NAID 10030821391

Related Pictures

★リンクテーブル★

リンク元	「栄養膜」「栄養外胚葉」「trophoectoderm」
拡張検索	「trophectodermal」

「栄養膜」

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