amnion

[ am-nee-uhn ]

noun

, plural am·ni·ons, am·ni·a [am, -nee-, uh].

1. Anatomy, Zoology. the innermost of the embryonic or fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended.
2. Zoology. a similar membrane of insects and other invertebrates.

amnion

/ ˈæmnɪən /

noun

1. the innermost of two membranes enclosing an embryonic reptile, bird, or mammal See also chorion

amnion

/ ăm′nē-ən /

1. A thin, membranous sac filled with a watery fluid (called the amniotic fluid ) in which the embryo or fetus of a reptile, bird, or mammal is suspended during prenatal development.
2. Also called amniotic sac

Word History and Origins

Origin of amnion¹

1660–70; < Greek, equivalent to amn ( ós ) lamb ( yean ) + -ion diminutive suffix

Word History and Origins

Origin of amnion¹

C17: via New Latin from Greek: a little lamb, from amnos a lamb

Example Sentences

Between these is a gelatinous substance, and within the amnion is a fluid, called the liquor amnii.

From Project Gutenberg

The whole being surrounded by two membranous coverings, the outer one called the chorion, and the inner one the amnion.

From Project Gutenberg

The amnion forms a small fold covering over the cephalic extremity of the embryo, which is deeply embedded in the yolk.

From Project Gutenberg

Both it and the stalk of the yolk-sack are enveloped by the amnion (am).

From Project Gutenberg

It adheres to the amnion and supplies it with blood-vessels (Bischoff).

From Project Gutenberg