In a groundbreaking development, scientists have generated synthetic human embryos using stem cells that sidestep the need for eggs or sperm, The Guardian reports. These model embryos, which mirror those in the earliest stages of human development, may offer a significant insight into the effects of genetic anomalies and the biological factors that contribute to recurrent miscarriage, according to scientists. Since lab-grown entities are illegal in the UK and most other nations, the development also poses significant ethical and legal concerns. The structures contain cells that would ordinarily develop into the placenta, yolk sac, and embryo itself but lack a beating heart and the beginnings of a brain, reports the Guardian. Also read: Scientists say taurine, present in meat, may extend life Prof Magdalena Żernicka-Goetz, of the University of Cambridge and the California Institute of Technology, described the work in a plenary address on Wednesday at the International Society for Stem Cell Research’s annual meeting in Boston. “We can create human embryo-like models by the reprogramming of [embryonic stem] cells,” she told the meeting. According to The Guardian, the use of synthetic embryos in clinical trials is not anticipated to happen anytime soon. It is currently unknown if these structures have the ability to continue maturing past the initial stages of development, making their implantation into a patient's womb illegal. The goal of the research is to help scientists better comprehend the so-called "black box" period of development, which lasts for only 14 days in accordance with regulatory restrictions. They then pick up the development's course at a far later stage by examining donated embryos and pregnancy scans. Also read: Alzheimer's drug gets FDA panel's backing, setting the stage for broader use “The idea is that if you really model normal human embryonic development using stem cells, you can gain an awful lot of information about how we begin development, what can go wrong, without having to use early embryos for research,” Robin Lovell-Badge, the head of stem cell biology and developmental genetics at the Francis Crick Institute in London, told The Guardian. Previously, Żernicka-Goetz’s team and a rival group at the Weizmann Institute in Israel showed that stem cells from mice could be encouraged to self-assemble into early embryo-like structures with an intestinal tract, the beginnings of a brain and a beating heart. Since then, a race has been under way to translate this work into human models, and several teams have been able to replicate the very earliest stages of development. The current research from the Cambridge-Caltech lab has not yet been fully described in a scholarly article. However, addressing at the conference, Ernicka-Goetz recounted growing the embryos to a level barely past the point at which a natural embryo would develop after 14 days. Also read: Did humans 3000 years ago have bigger brains than us? The model structures, which were each developed from a single embryonic stem cell, have begun to undergo gastrulation, a developmental stage in which the embryo changes from being a continuous sheet of cells to generating discrete cell lines and establishing the basic axis of the body, the Guardian reports, citing Ernicka-Goetz. The model demonstrated the presence of primordial cells, which are the precursor cells of egg and sperm, although the embryo at this stage does not yet have a beating heart, a functioning gut, or the beginnings of a brain. The development highlights how rapidly the science in this field has outpaced the law, and scientists in the UK and elsewhere are already moving to draw up voluntary guidelines to govern work on synthetic embryos. “If the whole intention is that these models are very much like normal embryos, then in a way they should be treated the same,” Lovell-Badge told the Guardian. “Currently in legislation they’re not. People are worried about this.” Read more: Scientists say taurine, present in meat, may extend life