self-directed evolution, filling in the gaps

Reuters | For first time, scientists grow two-week-old human embryos in lab
Scientists have for the first time grown human embryos outside of the mother for almost two full weeks into development, giving unique insight into what they say is the most mysterious stage of early human life.

Scientists had previously only been able to study human embryos as a culture in a lab dish until the seventh day of development when they had to implant them into the mother's uterus to survive and develop further.

But using a culture method previously tested to grow mouse embryos outside of a mother, the teams were able to conduct almost hour by hour observations of human embryo development to see how they develop and organize themselves up to day 13.

"This it the most enigmatic and mysterious stage of human development," said Magdalena Zernicka-Goetz, a University of Cambridge professor who co-led the work. "It is a time when the basic body shape is determined."

The work, covered in two studies published on Wednesday in the journal Nature and Nature Cell Biology, showed how the cells that will eventually form the human body self-organize into the basic structure of a post-implantation human embryo.

"Embryo development is an extremely complex process and while our system may not be able to fully reproduce every aspect of this process, it has allowed us to reveal a remarkable self-organizing capacity ... that was previously unknown," said Marta Shahbazi, a researcher at Britain's University of Cambridge who was part of the research teams.

Robin Lovell-Badge, an expert in stem cells at Britain's Francis Crick Institute who was not directly involved in this work, said it provided "a first glimpse" of how the early human embryo develops at the point when it would usually implant in the womb lining, becoming invisible and impossible to study.