The techniques and concepts that have resulted in the identification and isolation of embryonic stem cells have come from studies with mouse teratocarcinomas. Embryonic stem cells isolated from normal mouse embryos may be grown in tissue culture and new genetic modifications introduced into them. They may then be used to form chimeric mice, which are able to transmit the new mutations in their germ line. This has resulted in fully experimental mammalian genetics.
In addition to this genetic inheritance we might also consider the huge impacts of these ideas. Developmental cell biology now informs us about the plasticity as well as stability of the differentiated state, and stem cell biology is becoming a powerful new paradigm for clinical advances. The future of stem cell therapies will be discussed.