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Amniotic sac

Amniotic sac
A drawing of the amniotic sac from Gray's Anatomy.
The amniotic sac opened during afterbirth examination.
Dorlands/Elsevier s_01/12716695

The amniotic sac is the sac in which the fetus develops.

Some sources consider it to be equivalent to the amnion,[1][2], while other sources consider it to consist of the amnion and the chorion.[citation needed]

It is also called the amniotic bubble because of its resemblance to a bubble.[citation needed]

When in the light, the amniotic sac is shiny and very smooth, but too tough to pierce through.



An artificial rupture of membranes (ARM), also known as an amniotomy, may be performed by a midwife or obstetrician. This is usually performed using an amnihook and is intended to induce or accelerate labour.


The presence of the amnion identifies humans as amniotes, along with reptiles, dinosaurs, birds, and other mammals, but not amphibians.

Amniotic fluid

Amniotic fluid is the watery liquid surrounding and cushioning a growing fetus within the amnion. It allows the fetus to move freely without the walls of the uterus being too tight against its body. Buoyancy is also provided.

See also


  1. ^ amnion at eMedicine Dictionary
  2. ^ s_01/12716695 at Dorland's Medical Dictionary
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Amniotic_sac". A list of authors is available in Wikipedia.
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