ABSTRACT
INTRODUCTION A crucial facet of human embryonic stem cell (hESC) research is to gain insight into cell differentiation and in how this differentiation can be directed to produce specific types of somatic cells. Besides differentiation into somatic cells, it became clear a few years ago that ESCs can also be coaxed into becoming both male and female germ cells in the laboratory (1-3). Not long thereafter, researchers were able to produce live offspring from sperm cells derived from mouse ESCs (4). These successes and the prospect that one day human gametes will be derived from ESCs have inspired hopes in some, fears in others. Although several technical problems will have to be solved before artificial gametes can be used in research and in the clinic, it is wise to consider prospectively the different possible applications and the ethical issues that would be involved.
