Synchronous embryonic development and uterine differentiation is crucial to successful implantation and to pregnancy outcome; reciprocal interactions between the implantation-competent blastocyst and receptive uterus are necessary for successful implantation. Implantation involves the interplay of numerous signaling molecules, and the process is complicated and varies across species. Therefore, investigations into embryo and uterus crosstalk, including comparative research among species are necessary to improve reproductive biomedicine and animal husbandry. We herein focus on species-specific morphological changes, hormonal control, and molecular interactions that occur in the uterus and embryo during implantation in laboratory animals.