EXTRACELLULAR-MATRIX AND THE IMPLANTATION CASCADE IN PIGS

The structural and functional alterations of uterine epithelial cells that permit the apical-apical union of conceptus and uterine epitheliu m are complex and are likely to involve many different adhesion molecu les with distinct but inter-related functions. A number of changes in the molecular composition at the apical surface of uterine epithelial cells associated with the transition from the pre-receptive to the rec eptive state in the pig uterus are reviewed. Molecules that function i n the adhesion cascade resulting in implantation are represented by a variety of adhesion systems. However, integrins are probably the domin ant adhesion systems because their capacity to mediate adhesion is lin ked to their activation by engaging other surface molecules.