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trophoblast

 
Dictionary: tro·pho·blast   (trō'fə-blăst') pronunciation

n.
The outermost layer of cells of the blastocyst that attaches the fertilized ovum to the uterine wall and serves as a nutritive pathway for the embryo. Also called trophoderm.

trophoblastic tro'pho·blas'tic adj.

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Dental Dictionary:

trophoblast

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(trof′ o-blast)
n

The layer of peripheral embryonic cells from which the placenta is formed.

Veterinary Dictionary:

trophoblast

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The peripheral cells of the blastocyst, which attach the fertilized ovum to the uterine wall and contribute to the placenta and the membranes that nourish and protect the developing organism. The inner cellular layer is the cytotrophoblast and the outer layer is the syntrophoblast.

Wikipedia:

Trophoblast

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Trophoblast
Blastocyst English.svg
Blastocyst with an inner cell mass and trophoblast.
Gray32.png
Section through ovum imbedded in the uterine decidua. Semidiagrammatic.

am. Amniotic cavity.
b.c. Blood-clot.
b.s. Body-stalk.
ect. Embryonic ectoderm.
ent. Entoderm.
mes. Mesoderm.
m.v. Maternal vessels.
tr. Trophoblast.
u.e. Uterine epithelium.
u.g. Uterine glands.
y.s. Yolk-sac.
Gray's subject #6 46
Days 6
Gives rise to caul
MeSH Trophoblasts

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.

Contents

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 amniotic sac or caul.

Differentiation

The trophoblast proliferates and differentiates into 2 cell layers:

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

Additional images

See also

External links


 
 

 

Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Trophoblast" Read more