Cell adhesion
Cell adhesion molecules are degraded by syncytiotrophoblast secretion of Tumor necrosis factor-alpha. This inhibits the expression of cadherins and beta-catenin. Cadherins are cell adhesion molecules, and beta-catenin helps to anchor them to the cell membrane. Inhibited expression of these molecules thus loosens the connection between decidual cells, permitting the syncytotrophoblasts and the whole embryo with them to invade into the endometrium.