The extracellular matrix of the human fetal membranes: structure and function

The human fetal membranes are genetically identical to the fetus and form a highly specialized interface between mother and fetus, of considerable significance to the successful maintenance and termination of pregnancy in the higher vertebrates. Additionally, the upright posture of women presents these tissues with a greater mechanical challenge than in other species. The major extracellular matrix components providing tensile strength and elastic recoil are reviewed, as well as the key enzyme, activator/inhibitor system responsible for their remodelling and breakdown. However, this fails to convey the important concept that the matrix components are bound to each other and to the cells involved in their formation and organization. These matrix components are collectively responsible for the biomechanical properties of the tissue, but they must also be considered as dynamic elements of a broader signalling system, which include hormonal autocrine/paracrine systems. A unifying hypothesis is presented, which attempts for the first time to bring these two facets of the matrix together, which permits a potential coordination of local events at the maternal-fetal interface leading to parturition. In order to understand fully both the normal biology and the pathobiology of these tissues, such integration of the cellular and extracellular signalling pathways must be achieved.