A year ago, a Harvard study suggested that the medical dogma that women have a limited supply of eggs was wrong, exciting much comment in the media. Jonathan L. Tilly claimed that he could inject infertile mice with blood cells and that germ cells in the blood could become new eggs. This raised hopes that women might be able to overcome the age barrier for having children and that infertility due to chemotherapy could be overcome. Alas, a paper from another Harvard researcher disputes this in the journal Nature. In any case, many scientists had been sceptical of the revolutionary discovery. The review of Tilly's far-reaching claim found that his eggs could not develop into the mature eggs which are needed for a successful pregnancy.