The signals and molecular pathways involved in implantation, a symbiotic interaction between blastocyst and endometrium involving adhesion and tissue invasion.

Implantation is a complex process requiring the interaction of the blastocyst, and subsequently the developing embryo with the endometrium. Initially, the detailed cellular interactions implicated in this process were defined. More recently, many signals and molecular pathways are recognized that induce, or regulate the complex series of interactions required for implantation. In this review, the cellular and molecular interactions that take place during implantation are discussed.