Inbred mouse strains are defined as colonies produced by a minimum of 20 generations of brother-sister mating, traceable to a single founding pair. This mating structure results in animals that are genetically identical within each inbred strain (i.e., fundamentally free of genetic variants that could increase variation in experimental results).
Charles River uses a pyramid mating system coupled to a foundation colony for all of Charles River inbred mice strains. In this system, the foundation colony serves as the genetic and health standard and provides breeders for the top level of the pyramid in every barrier room.
This top level, the nucleus colony, is composed of a relatively small number of pedigreed brother-sister mating pairs that produce breeders for the next level of the pyramid, in addition to replenishing itself. In large colonies, the next level is called the expansion colony, and it provides breeders to the production colony, which in turn produces the animals that are commercially available.
Frequently Asked Questions (FAQs) for Inbred Mice
Why are inbred mice commonly used in research?
Inbred and F1 hybrid strains are frequently the mouse models of choice for research because of their unique and stable phenotypic traits, and hence, uniformity, and predictable experiment response.
How are inbred mouse colonies managed?
Colony management for inbred mouse strains includes a pyramidal, multi-colony structure and the maintenance of detailed breeding records. At the apex of the pyramid is the foundation colony, which are housed in isolators. Foundation colonies are the source of founder breeders for the brother-sister mated, pedigreed nucleus colonies in barrier rooms. Foundation breeders are reintroduced into each barrier room nucleus colony every three to five years to control genetic drift of inbred mice.