Overarching the main research areas at the TiHo are the replacement and supplementary methods to animal experimentation as an overriding principle in research and teaching. Against this background, the so-called "Virtual Center for Alternative and Complementary Methods to Animal Experiments" exists at the TiHo, in which the topic is dealt with in a large number of projects. In addition, there is a research network "R2N - Replace and Reduce from Lower Saxony - replacement and supplementary methods for future-oriented biomedical research", in which new methods are established in the sense of the 3R principle, which help to avoid and reduce animal experiments. In addition to the TiHo, the Hannover Medical School, the Twincore, the German Primate Center Göttingen, the Fraunhofer Institute for Toxicology and Experimental Medicine, the University Medical Center Göttingen and the Gottfried Wilhelm Leibniz University are involved in the research network. The aim is to reduce animal experiments in research and to use them only as a last resort. The Ministry of Science and Culture of Lower Saxony is funding this Lower Saxony research network with a total of 4.5 million euros for 4 years.