Integrins, endometrial maturation, & human embryo implantation

Cell-cell and cell-extracellular matrix interactions are fundamental proces ses involved in cell migration and tissue remodeling. Both the cyclic regen eration of the human endometrium during the menstrual cycle as well as the process of embryo implantation involve such dynamic interactions. It has be come quite clear that integrin adhesion molecules expressed on the surface of cells play critical roles in the transmission of signals from the extrac ellular milieu to the cells. It is these signals that presumably regulate t he behavior of these cells during major morphogenetic processes. In recent years, work in human endometrium and trophoblasts has uncovered both the re gulated and constitutive expression of integrin subunits and their extracel lular matrix ligands in these tissues. In addition, attempts have been made to correlate pathological states related to either infertility or abnormal pregnancy to the aberrant expression of several of these integrins. The pu rpose of the present review is to describe briefly our present state of kno wledge of the expression of integrins in human endometrium and trophoblasts and provide the reader with the necessary background needed to understand, at the cellular and molecular levels, processes in reproduction such as em bryo implantation.