Morphogenesis of the human preimplantation embryo: bringing mechanics to the clinics

During preimplantation development, the human embryo forms the blastocyst, the structure enabling uterine implantation. The blastocyst consists of an epithelial envelope, the trophectoderm, encompassing a fluid-filled lumen, the blastocoel , and a cluster of pluripotent stem cells, the inner cel l mass. This specific architecture is crucial for the implantation and further development of the human embryo. Furthermore, the morpholog y of the human embryo is a prime determinant for clinicians to assess the implantation potential of in vitro fertilized human embryos, which constitutes a key aspect of assisted reproduction technology. Therefore, it is crucial to understand how the human embryo builds the blastocyst. As any material , the human embryo changes shape under the action of forces. Here, we review recent advances in ou r understanding of the mechanical forces shaping the blastocyst. We discuss the cellular processes responsible for generating morphogenetic forces that were studied mostly in the mouse and review the literature on human embryos to see which of them may be conserved. Based on the specific morphological defects commonly observed in clinics during human preim-plantation development, we discuss how mechanical forces and their underlying cellular processes may be affected. Together, we propose that bringing tissue mechanics to the clinics w i l l advance ou r understanding of human preimplantation development, as wel l as ou r ability to help infertile couples to have babies.

Automated summary

The specific architecture of the blastocyst is crucial for the implantation and further development of the human embryo. Understanding the process of how the human embryo builds the blastocyst can enhance our understanding of preimplantation development and aid infertile couples in conceiving.