But medical science did not arrive at this stage overnight.

The art of transplantation has been developed over many years - since the year 200 BC, according to one legend.

It was then that Pien Csiao and Hua To are said to have performed the world's first heart transplant.

Modern developments

Modern clinicians prefer to date the development of the procedure to the 18th century, when doctors experimented with animals and humans.

Early attempts at transplantation failed, but during the first half of the 20th century techniques were honed until, in 1954, the world's first recognized organ transplant took place in America.

Dr Joseph Murray successfully transplanted a kidney in an operation in Boston, Massachusetts.

In the mid-60s, the first pancreas and liver transplants took place, and doctors proved their ability to save lives by replacing diseased organs with healthy ones.

The first heart transplant was a major breakthrough

Next they aimed for the big one - the heart.

Dr Christiaan Barnard, a South African surgeon, took medicine past this milestone in December 1967 when he transplanted a whole human heart from one person to another.

Since then the procedure has changed from an experimental operation to an established treatment for advanced heart disease.

Range of operations

Doctors expanded their repertoire as they perfected techniques and developed new drugs.

In 1981, the first heart and lung transplant took place and has been followed by an increasing number of successful operations on the major organs.

There are two major barriers to transplantation - acceptance and availability.

An organ cannot be taken from one person's body and simply placed into another's.

There has to be some genetic similarity between the recipient and the donor to prevent rejection, which is why organs donated by family members have a better chance of being accepted.

Rejection occurs when the recipient's immune system identifies the new organ as a threat and attacks it.

Tissue acceptance

But medical breakthroughs such as tissue typing and the use of drugs known as immunosuppressants have made more transplants possible and mean transplant recipients will survive longer.

The second barrier, availability, continues to be a problem, as demand for organs far outstrips the number donated.

This has led to a blackmarket trade in organs and a call for the sale of much needed body parts to be legalised.

Last June the International Forum for Transplant Ethics said in The Lancet that the international shortage of kidneys is so serious that people should be encouraged to overcome their horror at organ sales.

It is not only the major organs which are in demand. There is a great need for corneas, heart valves, bone and also for skin.

In response to this need, campaigning organisations have been founded around the world to encourage people to become donors.

The future looks set to bring further advances as neurologists experiment on brain transplants, biotechnologists experiment with cross-species transplants and cancer specialists in Manchester prepare for the world's first testicular transplant.

Many of the advances raise huge ethical questions.