For the first time, real-time footage of human embryos being implanted into an artificial uterus has been recorded.

This remarkable achievement, published in the journal Advances in Science, offers an unparalleled glimpse into one of the crucial stages of human development.

Implantation failure is a leading cause of infertility, responsible for 60% of miscarriages. Researchers aim to enhance understanding of the implantation process to improve fertility results in both natural conception and in vitro fertilization (IVF).

“We can’t observe this, due to the transplantation in the mother,” stated Dr. Samuel Ojosnegros, head of bioengineering at the Institute of Bioengineering (IBEC) and the lead author of the study, as reported by BBC Science Focus.

“Thus, we required a system to observe how it functions and to address the primary challenges to human fertility.”

Implantation marks the initial phase of pregnancy, where the fertilized egg (developing embryo) attaches to the uterine lining, allowing it to absorb nutrients and oxygen from the mother—vital for a successful pregnancy.

To investigate this process, the research team developed a platform that simulates the natural uterine lining, utilizing a collagen scaffold combined with proteins essential for development.

The study then examined how human and mouse embryos implant onto this platform, uncovering significant differences. Unlike mouse embryos that adhere to the uterine surface, human embryos penetrate fully into the tissue before growing from within.

“Human embryos are highly invasive,” said Ojosnegros. “They dig a hole in the matrix, embed themselves, and then grow internally.”

The footage indicated that the embryo exerts considerable force on the uterus during this process.

“We observed that the embryo pulls, moves, and rearranges the uterine matrix,” stated Dr. Amélie Godeau, co-first author of the research. “It also responds to external force cues. We hypothesize that contractions in vivo may influence embryo transfer.”

According to Ojosnegros, the force applied during this stage could explain the pain and bleeding many women experience during implantation.

Researchers are currently focused on enhancing the realism of implantation platforms, including the integration of living cells. The goal is to establish a more authentic view of the implantation process, which could boost the likelihood of success in IVF, such as by selecting embryos with better implantation potential.

“We understand more about the development of flies and worms than our own species,” remarked Ojosnegros. “So enjoy watching the film.”

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