US Scientists are preparing to perform the world's first full-face transplant. The 24-hour operation involves lifting an entire face from a dead donor - including nose cartilage, nerves and muscles - and transferring them to someone disfigured by burns or other injuries.
A team at the University of Louisville in Kentucky has submitted a 30-page request to the university's ethics committee, New Scientist magazine reported last week.
Mr Peter Butler, a surgeon at London's Royal Free Hospital, called for a debate on the procedure in 2002. The Royal College of Surgeons for England and Wales urged caution and decided last year that, for the time being, the risks outweighed the possible benefits.
But John Barker, leader of the Louisville team, told New Scientist: "Caution by itself will not get us any closer."
Faces have been replaced before. In 1994, a nine-year-old child in northern India lost her face and scalp in a threshing machine accident. Her parents raced to hospital with her face in a plastic bag and a surgeon managed to reconnect the arteries and replant the skin.
There have been similar successes in the US and Australia.
Hands have been transplanted, as well as thighs and knee bones, and a one-month-old baby girl survived a hand and arm transplant.
Transplants of kidneys, lungs, hearts and other tissue are now routine: the only constraint is a shortage of donors.
But a full-face transplant - of the kind used on Nicolas Cage and John Travolta in the science-fiction thriller Face/Off - is a bigger challenge. More than 30 muscles are involved in facial movements - it takes 17 muscles simply to smile.
Surgeons would need to save not just the donor's skin - from hairline to jawline and from ear to ear - but also the nose, mouth and lips, eyebrows and eyelids, subcutaneous fat, some of the muscles, the nasal substructure and the nerves.
Then they would have to painstakingly reconnect all of this to someone rendered almost unrecognisable by burns or scarring. The recipient would then require a lifetime's supply of immunosuppressive drugs to maintain the new face.
Some burns victims have had more than 50 skin-graft operations to rebuild faces that they believe to be still hopelessly disfigured. Surgeons argue that whole-face transplants would produce better results.
New Scientist worked with a television company, Mentorn, and an animation firm to conduct a "virtual transplant", stretching the facial skin of a virtual donor over the bone structure of a virtual patient.
Appearance is dictated not just by skin, but by bone structure, and surgeons are not sure how closely a reconstructed face would resemble a donor's at the end of the operation. The technical challenges are huge. So are the ethical dilemmas.