Barcelona, Spain - August 17, 2025 For the first time, researchers at the Institute for Bioengineering of Catalonia (IBEC) and Dexeus University Hospital have recorded a human embryo implanting in real time. Using a 3D platform that simulates the uterus, the team captured the embryo exerting remarkable force as it penetrated uterine tissue. Failure of implantation is a leading cause of infertility, responsible for 60% of spontaneous abortions. Until now, scientists could only study snapshots of the process. “We have observed that human embryos burrow into the uterus, exerting considerable force during the process. These forces are necessary because the embryos must be able to invade the uterine tissue, becoming completely integrated with it. It is a surprisingly invasive process,” said Samuel Ojosnegros, lead researcher. The embryo uses both enzymes and mechanical traction to push through collagen-rich tissue, forming specialized connections to maternal blood vessels. “The embryo opens a path through this structure and begins to form specialised tissues that connect to the mother's blood vessels in order to feed,” Ojosnegros added. Co-first author Amélie Godeau noted that the embryo actively remodels its environment, pulling and reorganizing the uterine matrix, suggesting that natural uterine contractions may influence implantation success. The new lab platform enabled unprecedented real-time observation and mechanical analysis, revealing that human embryos fully penetrate tissues, unlike mouse embryos, which are enveloped by uterine folding. “Our platform has allowed us to quantify the dynamics and mechanical footprint of this complex process in real time,” said co-first author Anna Seriola, highlighting the potential impact on fertility research and assisted reproduction.