FIGURE 1.

The cellular structure of the fetal membranes and their biophysical forces. The human fetal membranes consist of a multi-layered structure which surround the fetus in utero. It is composed of the amnion, chorion and decidua (upper box). Biophysical forces are placed on these fetal membranes (lower box depicted looking down onto the apical surface of the amnion epithelium). (A) Linear physical forces due to multi-directional stretching of the fetal membranes adherent to the decidua. (B) Dynamic physical forces on the fetal membranes due to fetal movements, Braxton Hicks contractions and eventually labor. (This Figure was created using BioRender).