CD-1 IGS mice are outbred mice derived from a group of outbred Swiss mice developed at the Anti-Cancer Center in Lausanne, Switzerland. They were imported to the US in 1926 and to Charles River in 1959. The CD-1 IGS mice are generally used for genetics, toxicology, pharmacology, and aging research. C57BL/6 mice are inbred mice developed by C.C. Little in 1921 at The Bussey Institute for Research in Applied Biology.
The C57BL/6 mice are used for transgenic and knockout model development (the wild-type C57BL/6 mice are a good control), as well as, obesity and immunological studies. There are advantages to using either outbred or inbred mouse strains depending on your research. Outbred mice have more genetic diversity, are more robust, and produce larger litter sizes than inbred mice. Inbred mice are almost genetically identical, which allows for easier interpretation of experiments.
It is important to keep these factors in mind when selecting either CD-1 IGS or C57/BL6 mouse primary cells for your studies.