US surgeons plan to carry out the world's first human face transplant.
Surgeons say they have the skills to do a face transplant
BBC News Online what it would involve.
What is a face transplant?
A face transplant, according to the surgeons who say they could carry it out, would involve removing the face of a dead person and placing it on someone who is still alive.
The donor and patient would have similar skin tone and the same blood type and would be of comparable age.
Has it been tried before?
The procedure has not been tried on a living human before.
A plastic surgeon in the US says he has transplanted the face of one dead person onto another dead person.
Scientists have successfully carried out face transplants on animals, namely rats and dogs.
Surgeons in India have successfully replanted the face of one patient. However, normal appearance was affected and muscles were damaged.
What would the procedure involve?
There are a number of ways surgeons could transplant the face of one person onto someone else.
British surgeons are believed to be considering a method which would involve removing the skin and fat from a dead person's face and placing it over the facial muscles of a living patient.
Surgeons in the US are understood to be considering a more complex operation.
They want to remove the skin, fat and facial muscles from the dead person's face and place them on the patient.
This type of surgery is by no means straight-forward. Nerves in the muscle would have to be attached to nerves in the patient's head.
Could these procedures work?
The Royal College of Surgeons of England says it is technically possible.
Advances in anti-rejection drugs which would need to be taken by patients for the rest of their life is responsible for their new-found optimism.
However, the fact remains that there have been no human trials of this procedure in live patients and nobody really knows what the long-term effects would be.
Sir Peter Morris of the Royal College of Surgeons has warned that there is a real risk that the procedure will not work.
What would the patient look like?
Nobody really knows what a face transplant recipient would look like.
Researchers have created a computer model which suggests patients would neither look like themselves nor the dead donor.
However, they believe the recipient would keep more of their own characteristics, not least because the tissue is being placed over their facial skeleton.
Nevertheless, if the transplant involves the transfer of muscle tissue as well as facial fat and skin they may have less movement in their face than before the operation.
What are the sticking points?
A report by a working group of the Royal College of Surgeons suggests there are two major sticking points.
The first is the long-term physical effects - whether a patient's immune system would be likely to reject the new face.
The risks of rejection are relatively high. Senior surgeons estimate one in 10 patients could suffer rejection within six weeks.
Up to half could suffer chronic rejection after a year and could suffer serious problems.
In order to reduce the risks of rejection, the patient would have to take powerful immunosuppression drugs.
These drugs can increase the risks of a range of health problems, including heart disease and cancer.
Unlike other transplants, face transplants are about improving a person's quality of life and not saving it. Therefore, the long-term effects of taking these drugs are important.
The second major factor is the psychological effects - both on the patient and on the donor's family.
There are doubts that families would be willing to have the face of their dead loved one transplanted onto someone else.
For instance, how would these families react if they were to meet or see the patient?
For their part, the patient would have to come to terms with the fact that they do not look the way they did before.
They would also have to be comfortable wearing someone else's face. This cannot be taken for granted.
The man who received the world's first hand transplant asked for it to be removed, partly because he didn't like having somebody else's hand.