breeding stocks, derivation of selected strains or congenic production, surgical manipulations, embryo conservation, and bioinformatics.
TJL develops mutant strains of mice as well as accepting mice from scientists who wish to make them available to other scientists. These mice from external sources may be spontaneous mutations, or they may be induced mutations. The laboratory also maintains pedigreed stocks of mouse strains using breeding programs that are designed to ensure their genetically unique qualities. Mice that are accepted by TJL must all be cesarean rederived to ensure that they are disease free. At this point they become Jackson Laboratory (JAX) mice and are distributed as such according to TJL policies. Internally, TJL has divided its 1,800 or so strains of mice into seven categories, each managed in a separate subunit known as a resource (instead of a department or division):
The largest numbers of mice are distributed from the production colonies (Animal Resources) (1.6 million annually); the Induced Mutant, Mouse Mutant, and Special Mouse Stocks Resources each distribute 10,000–12,000 mice annually.
The newest and fastest-growing resource is the Induced Mutant Resource (IMR), which may include about 235 strains at any one time. Until this resource was initiated in 1992, TJL distributed only mice developed by its in-house research staff. Almost all mice in the IMR originate outside TJL. The original plan for this resource was that approximately 50 percent of the strains included would be requested from authors of published papers and about 50 percent would be offered by external scientists. The interest in entering externally produced mutants into TJL has been so great, however, that a review panel has been established to select those to be included. During 1995,