Bbc Inside Science

We still know very little about exactly how the embryo forms out of a mass of dividing cells in those crucial first weeks after conception. This is also the time when many miscarriages occur, and scientists want to understand why. Couples going through IVF donate spare embryos for research and scientists are permitted to study them in a test tube, or in vitro, allowing them to grow and develop for up to 14 days. This 14 day rule is abided by globally, and it’s enshrined in the Human Fertilisation and Embryology Act in the UK. Thirty years ago no-one could keep these embryos alive for more than a few days but recently the techniques have moved on and they have been cultured for nearly 14 days. So should the 14 day rule be extended? Gaia Vince discusses this question with bioethicist professor Insoo Hyun of Case Western University and Harvard Medical School.There are other ways of studying this early development that don’t involve growing an actual embryo, and that’s by using just a few stem cells from it. The