Cadence of procreation: orchestrating embryo-uterine interactions

Embryo implantation in eutherian mammals is a highly complex process and requires reciprocal communication between different cell types of the embryo at the blastocyst stage and receptive uterus. The events of implantation are dynamic and highly orchestrated over a species-specific period of time with distinctive and overlapping expression of many genes. Delayed implantation in different species has helped elucidate some of the intricacies of implantation timing and different modes of the implantation process. How these events are coordinated in time and space are not clearly understood. We discuss potential regulators of the precise timing of these events with respect to central and local clock mechanisms. This review focuses on the timing and synchronization of early pregnancy events in mouse and consequences of their aberrations at later stages of pregnancy.