IVF treatment pioneered on humans was used to set up breeding programmes in the 1980s for the endangered giant panda, an animal notoriously reluctant to reproduce both in the wild and in captivity.
Nearly 20 years later, scientists from the Laboratory for Reproductive Biology at the Institute of Biology in Peking believe that the work on the panda has important implications for humans.
The female giant panda can only become pregnant during a three-day period in any year. Why this is so is unclear. But the scientists are sure that the knowledge they are gaining through their investigations may help to explain some of the fertility problems encountered by humans.
"The pool of knowledge about the reproduction of mammals is very important for humans," said Dr Colin Ockleford, who is leading the British team from the Department of Pre-Clinical Sciences at the University of Leicester. "There are differences in reproductive systems across mammals but there are common features as well."
The scientists in both countries are working on the relationship between the mother and the embryo in the immediate period after fertilisation. Because the vast majority of failed pregnancies end at this point, they believe the way in which the embryo and the mother's womb interact at this early stage is crucial.
The investigations are complex but essentially involve a study of the way different enzymes and proteins that are present in the womb interact to allow the foetus to embed itself in the wall of the womb. The enzymes are predisposed to attacking the embryo, which interpret it as a "foreign body", but the proteins in some way inhibit this procedure.
"In theory, the embryo shouldn't stand a chance because it is just a tiny blob of jelly trying to embed itself into the much more massive wall of the womb," Dr Ockleford said. "We need to know what it is that allows the embryo to attach itself and develop, and what prevents the enzymes in the womb from destroying it.
"IVF is a low success procedure in both pandas and humans. One reason for this may well prove to be the balance between destructive enzymes, which actively seek to destroy the embryo before it has time to establish itself, and a group of proteins which act as inhibitors and restrict the behaviour of these enzymes, so allowing the pregnancy to continue."
The scientists believe that once the relationship between the embryo, the mother, the enzymes and the "inhibitor" proteins is better understood it will lead to improved fertility treatment because doctors will be able to tip the balance between the enzymes and proteins in favour of the embryo, giving it a greater chance of developing.
However, the Chinese are more interested in another benefit. The Chinese scientists involved in the project, while working at the laboratory which has lead the research into pandas, are specialists in a separate department dealing exclusively with human production.
By creating an atmosphere which reduces the effect of the proteins, scientists may increase the chances of a pregnancy failing - in other words, they would effectively create a morning-after pill, which the Chinese authorities, concerned at controlling their burgeoning population, would welcome.
"There must be a controlled balance between these tissues," Dr Ockleford said. "Once this mechanism and relationship is properly understood it may, in theory, be possible to tip the balance and increase the likelihood of pregnancy, or tip it the other way and increase the chance of failure. This way lies an individual's best chances of controlling their fertility."
1 The giant panda is a solitary animal, which means that it breeds infrequently. The female is on heat for only three days a year, during which she may only produce one egg in a 12-hour period.
2 It lives on bamboo, which has low nutritional value - so to obtain enough nourishment the panda has to eat for up to 14 hours a day.
3 The panda shares its habitat with a variety of species which are extremely valuable to hunters supplying the booming medicinal trade in south-east Asia, including deer, bear and musk deer. Even though trading in panda skins carries the death penalty in China, the fur is prized by collectors.
4 Between 1974 and 1988, the panda's mountainous bamboo habitat shrank by half. Agriculture, logging and China's huge population increase have taken their toll, to the extent that the animal is now confined mainly to 13 panda reserves.
5 With between 800 and 1,000 pandas left in the wild, and about 100 in captivity, it could possibly be extinct within a few decades.Reuse content