Scientists have grown an entity that closely resembles an early human embryo, without using sperm, eggs, or a womb.
The Weizmann Institute team says their "embryo model", made using stem cells, looks like a textbook example of a real 14-day-old embryo.
It even released hormones that turned a pregnancy test positive in the lab.
However, the research also raises major ethical and legal consequences as the use of synthetic embryos for clinical purposes is not legally imminent in the UK and most other countries. Implanting them into a patient's womb is currently illegal, and it remains uncertain whether these structures have the potential to progress beyond the earliest stages of development. Scientists at present are allowed to cultivate embryos in the lab for a duration of 14 days.