Welfare Aspects of Transgenic Animals

v Preface The quality of animal models used in biomedical research has increased substantially since the first successful microinjection of foreign DNA frag­ ments into a mouse zygote in the early 1980s. New well-defined animal models, developed either by micro injection techniques or by homologous recombination in embryonic stem (ES) cells, have become widely available and several classical animal models have now been replaced by these transgenic models. Transgenic animals also fulfill increasi