British scientists are seeking permission to create hybrid embryos in the lab by fusing human cells with rabbit eggs. If granted consent, the team will use the embryos to produce stem cells that carry genetic defects, in the hope that studying them will help understand the complex mechanisms behind incurable human diseases.

To make a hybrid embryo, a human skin cell would be taken from a person with motor neuron disease and injected into a hollowed-out rabbit egg. The resulting embryo would contain only a tiny amount of rabbit DNA in a microscopic structure that generates energy in the cell. The rest of the DNA would be human.