Stem cells, isolated from embryos could provide new cells, tissues or organs for transplantation.
Opinion varies according to the status accorded to a human embryo.
A significant number of people consider the use of an embryo for research purposes morally and ethically unacceptable.
UK research is regulated by the Human Fertilisation and Embryology Authority (HFEA)
Bills passed in 2001 and 2002 allow ‘spare’ embryos from IVF treatment to be used as a source of stem cells for research into serious diseases.