Stem cells to gametes: how far should we go?

Murine embryonic stem cells have recently been shown to be capable of differentiating in vitro into oocytes or sperm. Should these findings be duplicated using human embryonic stem cells, this would raise a number of social and ethical concerns, some specific to these particular developments, others shared with other aspects of stem cell research. This review outlines the properties of stem cells and their conversion to gametes. Concerns raised include embryo destruction, quality of gametes derived in this way, possibility for children with two male biological parents, movement towards germ line gene therapy and 'designer babies', and the future impacts on health service provisions. It is important that public discussion of some of these issues should take place.