Skip to main content
Select Source:

amnion

amnion An inner cellular layer (epithelium) surrounding the fluid-filled embryo sac of reptiles, birds, and mammals. The wall of this sac has two layers of epithelium, with mesoderm and coelomic space between. The outer layer is usually called the chorion. The amnion and chorion develop as folds in the ectoderm and mesoderm which grow up around the sides of the embryo, eventually covering it. The amniotic fluid within the sac provides a liquid environment for the embryo, necessary for animals that reproduce on land. It may also cushion the mammalian embryo against distortion by maternal organs pressing on it. Sometimes the term ‘amnion’ is applied to the entire embryo sac.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." A Dictionary of Zoology. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." A Dictionary of Zoology. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion-0

"amnion." A Dictionary of Zoology. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion-0

amnion

am·ni·on / ˈamnēˌän; -ən/ • n. (pl. - or -ni·a / -nēə/ ) the innermost membrane that encloses the embryo of a mammal, bird, or reptile. DERIVATIVES: am·ni·ot·ic / ˌamnēˈätik/ adj.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amnion

"amnion." The Oxford Pocket Dictionary of Current English. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amnion

amnion

amnion Membrane or sac that encloses the embryo of a reptile, bird, or mammal. The embryo floats in the amniotic fluid within the sac. This sac usually ruptures shortly before birth to discharge the fluid, commonly referred to as ‘the waters breaking’. See also uterus

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." World Encyclopedia. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." World Encyclopedia. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/amnion

"amnion." World Encyclopedia. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/amnion

amnion

amnion A membrane that encloses the embryo of reptiles, birds, and mammals within the amniotic cavity. This cavity is filled with amniotic fluid, in which the embryo is protected from desiccation and from external pressure. See also extraembryonic membranes.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." A Dictionary of Biology. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." A Dictionary of Biology. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion-1

"amnion." A Dictionary of Biology. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion-1

amnion

amnion (am-ni-ŏn) n. the membrane that forms initially over the dorsal part of the embryo but soon expands to enclose it completely within the amniotic cavity.
amniotic (am-ni-ot-ik) adj.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." A Dictionary of Nursing. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." A Dictionary of Nursing. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/amnion

"amnion." A Dictionary of Nursing. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/amnion

amnion

amnion (anat.) caul. XVII. — modL. — Gr. amníon, dim. of amnós lamb.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amnion-0

"amnion." The Concise Oxford Dictionary of English Etymology. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amnion-0

amnion

amnion See AMNIOTIC.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"amnion." A Dictionary of Earth Sciences. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"amnion." A Dictionary of Earth Sciences. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion

"amnion." A Dictionary of Earth Sciences. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amnion