Scientists have proved for the first time that sperm grown from embryonic stem cells can be used to produce offspring.
Professor Karim Nayernia and colleagues at the Georg-August University in Germany, took stem cells from a mouse embryo that was only a few days old and grew these cells in the laboratory.
Using a specialised sorting instrument they were able to isolate some stem cells that had begun to develop as sperm.
They encouraged these early-stage sperm cells, known as spermatogonial stem cells, to grow into adult sperm cells and then injected some of these into female mouse eggs.
The fertilised eggs grew and were successfully transplanted into female mice and produced seven babies.
The experiment was carried out using mice and produced seven babies, six of which lived to adulthood.
The discovery in mice could ultimately help couples affected by male fertility problems to conceive, and by understanding embryo developmental processes better, a host of other diseases might be treated using stem cells, they say.
The study is published in the journal Developmental Cell.
According to Professor Nayernia, who now works at Newcastle University in the UK, this is for the first time they have created life using artificial sperm. This will help them to understand how men produce sperm and why some men are unable to do this.