First synthetic human embryo raises ethical issues

Scientists have created the first synthetic human embryos - using no eggs or sperm - provoking deep ethical questions, according to reports.

The synthetic embryos - only days or weeks old - could help researchers study the earliest stages of human development and explain pregnancy loss.

Nobody is currently suggesting growing them into a baby.

But the rapid progress has outpaced discussions on how they should be dealt with ethically and legally.

Prof James Briscoe, from the Francis Crick Institute, said the field needed to "proceed cautiously, carefully and transparently" to avoid a "chilling effect" on the public.

The development of human synthetic embryos was announced at the annual meeting of the International Society for Stem Cell Research.

Synthetic embryos are also known as "embryo models", as they resemble embryos, for the purposes of research, rather than being identical to them.