Rat strain repositories.
More than 500 inbred rat strains have been developed during the past 100 years for a wide range of biomedical applications. In addition to these traditionally bred strains, many induced mutants and several thousand mutagenized sperm samples have recently been generated. At present this huge number of strains is mainly managed by two rat resource centers, the National Bio Resource Project for the Rat in Japan (NBRP-Rat) and the US based Rat Resource and Research Center (RRRC). These resource centers not only collect, maintain and distribute rat strains as animals or cryopreserved embryos and spermatozoa, but also perform additional tasks such as phenotypic and genetic characterization as well as microbiological cleaning. Furthermore, they support researchers through informative databases in the selection of rat strains for specific research purposes. These global rat resource centers are essential for successful and sustainable research using the rat as a model species.