Gene transfer into mammalian embryos

Transgenic mice provide a unique system fusing classical genetics with molecular biology. They enable the dissection of molecular mechanisms underlying the control of growth and differentiation, issues we only dreamed of 20 years ago. The transgenic technology can be expected to be applied also in areas like eugenetics of animal production systems as well as genetic farming. The technology does not give an acceptable alternative for the direct treatment of human disease. However it provides unique possibilities to study genetic defects in a genetically well-defined mammalian model system. The years to come will teach us which of these expectations will come true.