Researchers at the Institute for Bioengineering of Catalonia and Hospital Dexeus have captured the first real-time, three-dimensional images of a human embryo embedding itself in tissue that replicates the uterine lining. The time-lapse footage, published in Science Advances on 18 August, shows a nine-day-old embryo burrowing into a collagen-based gel designed to mimic endometrial tissue. By recording microscopic images every 20 minutes over 16–24 hours, the team documented how the embryo releases enzymes and pulls on surrounding tissue to carve a niche, a process lead author Samuel Ojosnegros describes as “surprisingly invasive.” Co-author Amélie Godeau added that the embryo also responds to external mechanical cues, suggesting uterine contractions may influence the success of implantation. The work offers a new window on a developmental phase that is normally hidden inside the body and difficult to study ethically or technically. Implantation failure is thought to cause roughly 60 percent of miscarriages, making it a leading factor in infertility. The researchers say their synthetic-uterus platform could help identify why some embryos fail to take hold and guide improvements in assisted-reproduction techniques.