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Fetal Membranes

The intrauterine cavity is composed of both fetal and maternal tissue and plays a vital role during pregnancy and parturition. Maternal tissues including: the cervix, myometrium, decidualized endometrium, and vagina are studied extensively in pregnant and non-pregnant conditions. In regards to fetal tissue the placenta has been studies extensively, while the fetal membranes are often ignored as it is mistakenly considered as a part of placenta.

Figure 1: Graphical Representation of In Utero Organs

Representation of the entire intrauterine cavity containing the (from outside-in): maternal cavity, uterus/myometrium, placenta, fetal membranes, amniotic fluid, and fetus. A) Represents the placenta, site of nutrients and oxygen exchange for the growing fetus. The placenta is attached to the maternal side by the myometrium and the fetal side through the fetal membranes. The black asterisk identifies tertiary chorionic villi, while the red and blue arrows represent arteries and veins respectively. B) Represents the umbilical cord in its external view (1), internal view (2), and cross-section (3). C) The description starts from the innermost layer (amnion) and ends at the uterus. Amnion epithelial cells (blue) are connected the first layer of the ECM called the basement membrane (orange)/ compact layer (orange strips). The fibroblast (top red), spongy (black), and reticular layers (bottom red) follow, containing stromal cells (purple). The chorion (beige) is connected to the ECM through a pseudo-basement membrane (orange). The chorion is made up of two types of cells: 1) chorion leave cells that contain vacuoles (dark yellow circles) and 2) the chorion trophoblast cells. The chorion interfaces with the decidua (green), connecting the fetal to the maternal compartments of the uterus.

Fetal membranes, connected to the placenta, are an integral component of uterine cavity providing structural support for the growing fetus until their disruption at term. As a rich source various biochemicals with diverse function, fetal membranes play a vital role in pregnancy and later on promoting parturition. The fetal membranes are made up of a single layer of amnion epithelial cells and chorion connected by a collagen rich extra cellular matrix containing mesenchymal cells. Thus, fetal membranes are unique in structure and distinct from the placenta. While the placenta provides oxygen, nutrients, and filters waste from fetal blood, the fetal membranes provide mechanical, immune, and endocrine functions to contain and protect the fetus.


Fetal membranes have a longevity of 10 months, duration of fetal life in utero. As a baby is delivered, fetal membranes are also delivered along with placenta, but they are not dead tissues at delivery. Fetal membrane cells are stem cell rich and the scientific community has identified these properties and utilizes their tissue regenerative properties for treating various conditions.

This website will constantly provide updates on fetal membranes’ importance during pregnancy, labor and delivery and recent research development from World’s experts

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