Definitions for "Amniotic sac"
Keywords:  amnion, sac, chorion, fetus, embryo
also called amnion. A lining inside the uterus that contains the fetus and the fluid that cushions the fetus. This fluid is called amniotic fluid. The term “water breaks” refers to the amniotic sac breaking; this often occurs at the beginning of labor.
The thin walled sac inside the uterus that surrounds the baby, amniotic fluid and the placenta during pregnancy. It has a capacity of about 4 to 5 liters at term. The wall of the sac is made up from the amnion, chorion and decidua, each of which are just a few cell layers thick, and which extends from the margin of the placenta. While each of the layers are in contact, they are not fused together. The sac serves to maintain the equilibration hydrostactic pressure within the uterus during pregnancy. During labor the sac transmits uniform pressure of the uterine contractions to the cervix for dilation.
(Amnion) - A thin, tough, membranous sac that encloses the embryo or fetus of a mammal, bird, or reptile. It is filled with a serous fluid in which the embryo is suspended.