amnion

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amnion

 [am´ne-on]
the innermost fetal membrane, which forms a sac filled with amniotic fluid that surrounds the embryo and later the fetus; as it enlarges it gradually obliterates the chorionic cavity and enfolds the umbilical cord. Called also bag of waters.
 Amnion, chorion, and other embryonic membranes surrounding the embryo of a placental mammal. From Dorland's, 2000.
amnion nodo´sum a nodular condition of the fetal surface of the amnion, usually appearing near the insertion of the cord; it may be associated with multiple congenital abnormalities, especially hypoplastic kidneys and oligohydramnios.

am·ni·on

(am'nē-on),
Innermost of the extraembryonic membranes enveloping the embryo in utero and containing the amniotic fluid; it consists of an internal embryonic layer with its ectodermal component and an external somatic mesodermal component; in the later stages of pregnancy the amnion expands to come in contact with and partially fuse to the inner wall of the chorionic sac; derived from the trophoblast cells.
Synonym(s): amnionic sac
[G. the membrane around the fetus, fr. amnios, lamb]

amnion

(ăm′nē-ən, -ŏn′)
n. pl. am·nions or am·nia (-nē-ə)
A thin, tough, membranous sac that encloses the embryo or fetus of a mammal, bird, or reptile. It is filled with a serous fluid in which the embryo or fetus is suspended.

am′ni·ot′ic (-ŏt′ĭk), am′ni·on′ic (-ŏn′ĭk) adj.

am·ni·on

(am'nē-on)
Innermost of the extraembryonic membranes enveloping the embryo and later the fetus, containing the amnionic fluid; it consists of an internal embryonic layer with its ectodermal component, and an external somatic mesodermal component; in the later stages of pregnancy, the amnion expands and partially fuses to the inner wall of the chorionic sac; derived from the trophoblast cells.
Synonym(s): amnionic sac.
[G. the membrane around the fetus, fr. amnios, lamb]

amnion

One layer of the fluid-filled double membrane surrounding the fetus before birth. The amnion is the inner of two membranes, the other being the chorion. The membranes normally rupture and release the AMNIOTIC FLUID (‘breaking of the waters’ before the baby is born.
Amnionclick for a larger image
Fig. 30 Amnion . A vertebrate embryo lying within the amnion.

amnion

an embryonic, fluid-filled sac which occurs in reptiles, birds and mammals (AMNIOTES). Formed from ECTODERM and MESODERM and containing a coelomic space (see COELOM), the amnion grows around the embryo and eventually roofs over and completely encloses it. It provides the fluid-filled space necessary for the development of the embryo of a land animal, and it also acts as a protective cushion.

Patient discussion about amnion

Q. what does it mean when an ultrasound shows an empty amniotic sac and no baby?

A. This exact thing happened with my friend who is now 22 weeks with her first baby. She had 2 additional sacs - both empty - and the doctor said that the pregnancy had probably started out as triplets but that only one of the embryos had actually established and continued to grow.

Her doctor said it is very common for a woman to have more than one egg fertilize but that in most cases the pregnancy continues as a singleton only. She told my friend that the empty sacs would just disappear through time (which they did) and that they posed no danger to her baby.

More discussions about amnion
References in periodicals archive ?
This Opera amnia project was inspired by a 1992 conference devoted to the composer, his works, and his legacy; among other things, the conference reinforced the need for new critical editions of Ingegneri's works to be created and made available to a new generation of scholars.
Graduating Somali student, Amnia Nasser, said she is prepared to work with government hospitals here.
Here are two more solutions having a fair number of common words: CHEVY FOIST GAULT BRAWL ROQUE JUNTA AMNIA RADII ALULA OPTIC TIMER OZONE FEIGN RHINO OGIVE WEBER TYPOS DESKS RAXED NEEDS QUAFF HOTCH SWEPT GOLEM UNBAR IVORY PIXIE AZURE AWAKE JORUM OVINE DONGA DICER ALIEN RENAL INGOT STADE BOILS TRESS DEITY
Demetrias is referred to as "Amnia," another nomen of the Anicii and Probi (for example, Amnius Anicius Iulianus, consul in 322:).