Established lines of human pluripotent stem cells provide a convenient tool for investigating cell differentiation in a way that is pertinent to human embryonic development, providing insights into the causes of birth defects and diseases such as cancer that involve aberrant cell proliferation and differentiation. In principle, human pluripotent stem cells, including embryonic stem and embryonic germ cells, are capable of differentiating into all of the cell types that are present in the adult human. They therefore have the potential to provide a source of tissues for replacement in diseases in which native cell types are inactivated or destroyed. Intense media and public interest has surrounded the announcement of human pluripotent stem cells derivation, focusing on the ethical implications of embryo-related work and on the prospects of an unlimited source of tissues for transplantation-based treatments. Recent studies have focused on identifying method for culture of these cells and inducing their differentiation into specific cell types.