Scientists have discovered a simple, efficient way to recreate the early structure of the human embryo from stem cells in the laboratory.
They say the new approach unlocks news ways of studying human fertility and reproduction.
Stem cells have the ability to turn into different types of cell and researchers have developed a method to organise lab-grown stem cells into an accurate model of the first stage of human embryo development.
This could benefit research into infertility by furthering understanding of how embryos develop, and the conditions needed to avoid miscarriage and other complications.
The embryo models can also be used to test conditions that may improve the development of embryos in assisted conception procedures such as IVF, the experts say.
The discovery comes after the researchers found that a human stem cell was able to generate the founding elements of a blastocyst, the very early formation of an embryo after a fertilised egg divides.
Professor Austin Smith, director of the University of Exeter’s Living Systems Institute, said: “Finding that stem cells can create all the elements of an early embryo is a revelation.
“The stem cells come from a fully-formed blastocyst, yet they are able to recreate exactly the same whole embryo structure.
“This is quite remarkable and unlocks exciting possibilities for learning about the human embryo.”
Only a few human embryos are available for study, so until now, scientists have largely focused on animal research, particularly mice, despite their reproductive systems differing significantly from humans.
Around one in seven couples in the UK has difficulty conceiving, experts say.
In the study, researchers arranged the stem cells into clusters and briefly introduced two molecules known to influence how cells behave in early development.
They found that 80% of the clusters organised themselves after three days into structures that looked like the blastocyst stage of an embryo, a ball of around 200 cells that forms from the fertilised egg after six days.
The team went on to show that the artificial embryos have the same active genes as the natural embryo.
Dr Ge Guo, of the University of Exeter’s Living Systems Institute, said: “Our new technique provides for the first time a reliable system to study early development in humans without using embryos.
“This shouldn’t be seen as a move towards producing babies in a laboratory, but rather as an important research tool that could benefit IVF and infertility studies”.
The research is published in Cell Stem Cell, funded by the Medical Research Council, and conducted by scientists at the University of Exeter’s Living Systems Institute, working with colleagues from the University of Cambridge.