at do we mean by 'Embryo'
Technically, the term embryo refers to the products of conception after implantation into the wall of the womb, usually nearly two weeks after fertilisation, up until the eighth week. On this site, we will intend the more common usage, where embryo refers to any stage up to 8 weeks. It is worth noting that most discussion around embryo research relates to the first two weeks (UK) or 15 days (US).
From the mid 1970s, IVF was being developed and research was carried out on spare embryos produced. This research helped to improve IVF techniques, as well as to better understand the earliest stages of human development. Research also shed light on a variety of inheritable disorders.
In America, embryo research is limited to spare embryos produced. It is not permitted to produce embryos for the purpose of experimentation. The laws regarding embryo research are not as strict in the UK.
Recent developments have changed the focus of the debate about embryo research. Embryos contain stem cells which, according to scientists, could be used to cure a wide range of conditions. Stem cells can be coaxed into growing cells of any other type, which makes them potentially very useful indeed. However, removing stem cells from an embryo will kill the embryo, which some people object to.