A team of researchers at the Institute for Bioengineering of Catalonia (IBEC) in Spain has succeeded, for the first time, in recording in real time and in 3D the implantation of a human embryo. This achievement opens up the possibility of investigating in greater depth the causes of infertility and discovering new assisted reproduction treatments.
Failure of embryo implantation in the uterus is one of the major barriers to pregnancy, and is associated with about 60 percent of miscarriages. This process, which occurs within days of a sperm fertilizing an egg, had, until recently, remained virtually invisible—implantation was only known from still images, and it wasn’t possible to follow its development in real time. Typically, it’s only possible to detect an embedded embryo several weeks after implantation, using ultrasound.
“We have observed that human embryos burrow into the uterus, exerting considerable force,” said Samuel Ojosnegros, lead author of the study, in a statement. “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.”
Studying the implantation of embryos into the uterine lining has always been approached from a genetic and biochemical perspective. This IBEC study emphasizes that implantation is a physical process too.
Making an Artificial Uterus to See the Unseeable
To capture the moment of implantation, the team developed a physical simulation of a uterus using an artificial collagen gel. This made it possible to observe—using fluorescence microscopy, a technique well-suited to imaging things at the cellular level—how the embryo interacts with the uterus in real time. “The embryo opens a path through this structure and begins to form specialized tissues that connect to the mother’s blood vessels in order to feed,” Ojosnegros said.