Successful implantation is the result of an intimate 'cross-talk' between the blastocyst and uterus in a temporal and cell-specific manner. Thus, both the uterine and embryonic events must be examined to better understand this process. Although various aspects and molecules associated with these events have been explored, a comprehensive understanding of the implantation process is still very limited. In this review, we have highlighted the importance of the blastocyst's activity state and the receptive state of the uterus in determining the 'window' of implantation. In this context, we provide a testable scheme that signifies the important roles of various key molecules in embryo-uterine interactions during implantation.
Copyright 2000 Academic Press.