EMBRYO RESEARCH: WHY SCIENTISTS WANT MORE THAN 14 DAYS TO STUDY EARLY DEVELOPMENT

An extension to the 14-day limit on research has been proposed and has support. But there are moral and ethical questions to consider

- DR HELEN PILCHER

Members of the British public surveyed by the Human Developmental Biology Initiative and UK Research and Innovation Sciencewise largely gave their backing to a controversial proposal recently. Of the 70 participants, most expressed support for extending the 14-day limit on the research of human embryos.

If a change to the law is successful, researchers will be able to grow and study cultured human embryos for longer periods of time. This subject has always raised moral and ethical concerns, but those in favour of the extension argue that it'll afford researchers unprecedented insights into human development, which could lead to significant improvements in fertility and health.

WHAT IS THE 14-DAY RULE?

In UK law, it's illegal to carry out research on laboratory-grown human embryos beyond 14 days of development. This includes 'spare' IVF embryos that have been donated for research purposes and embryos created with donated sperm and eggs.

Similar rules exist in other countries such as the US, Japan, China and the Netherlands - but while some are legally binding, others are just guidelines. There are countries, such as Germany and Russia, which don't currently permit any human embryonic research at all.

WHY IS THE CURRENT LIMIT SET AT 14 DAYS?

At 14 days, the embryo is a small and simple structure, made of two layers of cells. There's no head or heart, brain or spinal cord, nor recognisable organs of any kind. The embryo is made of stem cells that have the potential to form specialised cell types, such as neurons and muscle cells, but this has yet to happen.