Review: The evolving placenta: Different developmental paths to a hemochorial relationship

A C Enders, A M Carter

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into four main patterns: a transitory endotheliochorial condition; maternal blood released into a mass of trophoblast; maternal blood confined to lacunae; and fetal villi entering preexisting maternal blood sinuses. Although it might be considered logical that developing placentas would pass through an endotheliochorial stage to become hemochorial, this developmental pattern is seen only as a transient stage in several species of bats and sciuromorph rodents. More commonly a mass of trophoblast at the junction with the endometrium serves as a meshwork through which maternal blood passes, with subsequent organization of a labyrinth when the fetal vascular component is organized. The initial trophoblast meshwork may be cellular or syncytial, often leading to a similar relationship in the spongy zone and labyrinth. Old World monkeys, apes and humans have a lacunar stage prior to establishing a villous hemochorial condition. New World monkeys lack a true lacunar stage, retaining portions of maternal vessels for some time and initially forming a trabecular arrangement similar to though differently arrived at than that in the tarsier. In armadillos, preexisting maternal venous sinuses are converted into an intervillous blood space by intruding fetal villi. Variations from the major patterns of development also occur. The way in which the definitive placental form is achieved developmentally should be considered when using placental structure to extrapolate evolution of placentation.
OriginalsprogEngelsk
TidsskriftPlacenta
Vol/bind33
Udgave nummerSupplement
Sider (fra-til)S92-S98
ISSN0143-4004
DOI
StatusUdgivet - 2012

Fingeraftryk

Placenta
Mothers
Trophoblasts
Tarsiidae
Placentation
Endometrium
Rodentia

Citer dette

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title = "Review: The evolving placenta: Different developmental paths to a hemochorial relationship",
abstract = "The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into four main patterns: a transitory endotheliochorial condition; maternal blood released into a mass of trophoblast; maternal blood confined to lacunae; and fetal villi entering preexisting maternal blood sinuses. Although it might be considered logical that developing placentas would pass through an endotheliochorial stage to become hemochorial, this developmental pattern is seen only as a transient stage in several species of bats and sciuromorph rodents. More commonly a mass of trophoblast at the junction with the endometrium serves as a meshwork through which maternal blood passes, with subsequent organization of a labyrinth when the fetal vascular component is organized. The initial trophoblast meshwork may be cellular or syncytial, often leading to a similar relationship in the spongy zone and labyrinth. Old World monkeys, apes and humans have a lacunar stage prior to establishing a villous hemochorial condition. New World monkeys lack a true lacunar stage, retaining portions of maternal vessels for some time and initially forming a trabecular arrangement similar to though differently arrived at than that in the tarsier. In armadillos, preexisting maternal venous sinuses are converted into an intervillous blood space by intruding fetal villi. Variations from the major patterns of development also occur. The way in which the definitive placental form is achieved developmentally should be considered when using placental structure to extrapolate evolution of placentation.",
author = "Enders, {A C} and Carter, {A M}",
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Review: The evolving placenta: Different developmental paths to a hemochorial relationship. / Enders, A C; Carter, A M.

I: Placenta, Bind 33, Nr. Supplement, 2012, s. S92-S98.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Review: The evolving placenta: Different developmental paths to a hemochorial relationship

AU - Enders, A C

AU - Carter, A M

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N2 - The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into four main patterns: a transitory endotheliochorial condition; maternal blood released into a mass of trophoblast; maternal blood confined to lacunae; and fetal villi entering preexisting maternal blood sinuses. Although it might be considered logical that developing placentas would pass through an endotheliochorial stage to become hemochorial, this developmental pattern is seen only as a transient stage in several species of bats and sciuromorph rodents. More commonly a mass of trophoblast at the junction with the endometrium serves as a meshwork through which maternal blood passes, with subsequent organization of a labyrinth when the fetal vascular component is organized. The initial trophoblast meshwork may be cellular or syncytial, often leading to a similar relationship in the spongy zone and labyrinth. Old World monkeys, apes and humans have a lacunar stage prior to establishing a villous hemochorial condition. New World monkeys lack a true lacunar stage, retaining portions of maternal vessels for some time and initially forming a trabecular arrangement similar to though differently arrived at than that in the tarsier. In armadillos, preexisting maternal venous sinuses are converted into an intervillous blood space by intruding fetal villi. Variations from the major patterns of development also occur. The way in which the definitive placental form is achieved developmentally should be considered when using placental structure to extrapolate evolution of placentation.

AB - The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into four main patterns: a transitory endotheliochorial condition; maternal blood released into a mass of trophoblast; maternal blood confined to lacunae; and fetal villi entering preexisting maternal blood sinuses. Although it might be considered logical that developing placentas would pass through an endotheliochorial stage to become hemochorial, this developmental pattern is seen only as a transient stage in several species of bats and sciuromorph rodents. More commonly a mass of trophoblast at the junction with the endometrium serves as a meshwork through which maternal blood passes, with subsequent organization of a labyrinth when the fetal vascular component is organized. The initial trophoblast meshwork may be cellular or syncytial, often leading to a similar relationship in the spongy zone and labyrinth. Old World monkeys, apes and humans have a lacunar stage prior to establishing a villous hemochorial condition. New World monkeys lack a true lacunar stage, retaining portions of maternal vessels for some time and initially forming a trabecular arrangement similar to though differently arrived at than that in the tarsier. In armadillos, preexisting maternal venous sinuses are converted into an intervillous blood space by intruding fetal villi. Variations from the major patterns of development also occur. The way in which the definitive placental form is achieved developmentally should be considered when using placental structure to extrapolate evolution of placentation.

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