EXTRACELLULAR MATRIX-5 - ADHESIVE INTERACTIONS IN EARLY MAMMALIAN EMBRYOGENESIS, IMPLANTATION, AND PLACENTATION

Normal morphogenesis and differentiation depend heavily on the coordin ation of cell-cell and cell-extracellular matrix interactions. During early mammalian development, the first cell lineages to be established are extraembryonic (trophoblast and extraembryonic endoderm), which a re essential for satisfying the nutritional requirements of the develo ping embryo. This review emphasizes the importance of the cadherin fam ily of cell-cell adhesion molecules and the integrin family of extrace llular matrix receptors in mediating interactions between cells and th eir environment during early development. The review first discusses t he critical role of cell-cell interactions in fertilization and early lineage decisions that occur during pre- and peri-implantation develop ment in the mouse, using the calcium-dependent cell adhesion molecule E-cadherin as the primary example. The remainder of the review discuss es the importance of cell-ECM interactions in the further morphogenesi s and differentiation of the newly segregated lineages. The critical r oles of integrins in differentiation, migration, and invasion of troph oblast in both mouse and human are emphasized.