Amnionraum

The amnionraum, commonly referred to as the amniotic cavity or amniotic sac, is a fluid-filled space within the amnion that surrounds and protects the developing embryo and fetus during pregnancy. This structure is a critical component of the placenta and plays a vital role in ensuring the healthy development of the fetus.

The amnion is a thin, transparent membrane that forms early in pregnancy, typically around the third week of gestation. It develops from the epiblast, a layer of cells within the blastocyst, and eventually encloses the amniotic fluid, which cushions the fetus against mechanical shocks and temperature fluctuations. The amniotic fluid also facilitates fetal movement, allowing for the proper development of muscles and joints, and helps regulate the fetus’s internal temperature.

As pregnancy progresses, the amniotic cavity expands to accommodate the growing fetus. By the end of the first trimester, the amnionraum is fully formed and contains enough fluid to provide adequate protection and support. The volume of amniotic fluid typically reaches its peak between weeks 34 and 36 of gestation, after which it gradually decreases until birth.

The amniotic sac also plays a role in preventing infections from reaching the fetus by acting as a barrier. However, in some cases, premature rupture of the amnion (known as premature rupture of membranes or PROM) can lead to complications, such as increased risk of infection or preterm labor.

At the time of birth, the amniotic sac ruptures, allowing the fetus to emerge from the uterus. The fluid released during this process is often referred to as "breaking the waters," a natural sign that labor may be imminent. The amnionraum is essential for fetal development, providing a safe and stable environment until the moment of delivery.