New models of implantation: towards a whole better than the sum of parts

Recent advances in the development of stem-cell-based embryo models and endometrial assembloids have fuelled understanding of their respective biology. However, a faithful combined approach is required to truly advance our understanding of implantation processes. This mini-review considers the most recent developments in producing reliable in vitro models of the human endometrium and human embryo, and the next steps required to combine their respective potential. While the fundamental biology of implantation is the primary driver of in vitro model development, the combined effort of embryo and endometrial models to generate new models of implantation provides the opportunity to manipulate either compartment to further understand the aetiologies of reproductive dysfunction. Through combining both systems, their efforts are symbiotic, each extending the relevance and utility of their counterpart to generate a whole greater than the sum of its parts.