Researchers at Newcastle upon Tyne University want to take stem cells from a woman donor’s bone marrow and transform them into sperm through the use of special chemicals and vitamins.

Newcastle professor Karim Nayernia has applied for permission to carry out the work and is ready to start the experiments within two months.

The biologist, who pioneered the technique with mice, believes early- stage ‘female sperm’ could be produced inside two years. Mature sperm capable of fertilising eggs might take three more years.

Early-stage sperm have already been produced from male bone marrow. Taking stem cells from an adult donor removes the ethical problems associated with using embryos.

Researchers at the Butantan Institute in Brazil, meanwhile, claim to have turned embryonic stem cells from male mice into both sperm and eggs. They are now working on skin cells.