Amniotic sac

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

Some sources consider it to be equivalent to the amnion,, while other sources consider it to consist of the amnion and the chorion.

It is also called the amniotic bubble because of its resemblance to a bubble.

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

Amniotomy
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.

Diversity
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.