Researchers at Japan's Kyoto University have developed a way to use human iPS cells to mass-generate cells capable of turning into human eggs.

A group led by Professor Saitou Mitinori of Kyoto University's Institute for Advanced Study found a method to create base cells for reproductive cells from human iPS cells, and then change them into oogonia, which develop into ova.

The problem was that the amount of oogonia produced was too small.

When the researchers added a protein called BMP in culturing the base cells, they succeeded in producing huge amounts of oogonia.

The oogonia reportedly multiplied about ten billion-fold over roughly four months.

The group says it also successfully mass-generated, by the same methods, cells that develop into sperm.

Saitou said his team aims to apply the method to medical care, such as infertility treatment.