UK scientists have applied for permission to create embryos by fusing human DNA with cow eggs.
Researchers from Newcastle University and Kings College, London, have asked the Human Fertilisation and Embryology Authority for a three-year licence.
The hybrid human-bovine embryos would be used for stem cell research and would not be allowed to develop for more than a few days.
But critics say it is unethical and potentially dangerous.
The problem is that human eggs for research are in short supply and to obtain them women have to undergo surgery.
That is why scientists want to use cows' eggs as a substitute.
It would, though, technically be a chimera - a mixing of two distinct species into one.
clipped from: news.bbc.co.uk