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amnionenUK
am·ni·on A0260100 (ăm′nē-ən, -ŏn′)n. pl. am·ni·ons or am·ni·a (-nē-ə) A tough, thin membrane that forms a sac enclosing 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.
[New Latin, from Greek amneion, variant of amneios, amnion, and from amnion, amnion, both from amnos, lamb; akin to Irish úan, Latin agnus, and Old Church Slavonic agnę, lamb.]
am′ni·ot′ic (-ŏt′ĭk), am′ni·on′ic (-ŏn′ĭk) adj.amnion (ˈæmnɪən) n, pl -nions or -nia (-nɪə) (Zoology) the innermost of two membranes enclosing an embryonic reptile, bird, or mammal. See also chorion[C17: via New Latin from Greek: a little lamb, from amnos a lamb]am•ni•on (ˈæm ni ən)
n., pl. -ni•ons, -ni•a (-ni ə) the innermost membrane of the sac surrounding the embryo in reptiles, birds, and mammals, enclosing the amniotic fluid. [1660–70; < Greek amníon, derivative of amnós lamb (see yean)] am`ni•ot′ic (-ˈɒt ɪk) am`ni•on′ic, adj. am·ni·on (ăm′nē-ən) A sac of thin, tough membrane containing a watery liquid in which the embryo of a reptile, bird, or mammal is suspended. ♦ The watery fluid in the amnion is called amniotic fluid.amniocentesis, amnion - Amniocentesis is formed by amnion, the innermost membrane enclosing a fetus, and Greek kentesis, "pricking."See also related terms for mammal.Thesaurus| Noun | 1. |  amnion - thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)amnios, amniotic sacamniote - any member of the Amniotamammal, mammalian - any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milkfetal membrane - any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetussac - a structure resembling a bag in an animal |
TranslationsamnionenUK
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. 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 amnionQ. 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 amnionamnionenUK
Related to amnion: yolk sac, amnion nodosumSynonyms for amnionnoun thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)SynonymsRelated Words- amniote
- mammal
- mammalian
- fetal membrane
- sac
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