amnion(redirected from Amnionic sac)
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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.
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.
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.
See also related terms for mammal.
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|Noun||1.||amnion - thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)|
amniote - any member of the Amniota
mammal, 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 milk
fetal membrane - any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
sac - a structure resembling a bag in an animal