Two-way selection of a stock of Swiss albino mice for mammary tumorigenesis: establishment of two new strains (SHN and SLN).

Two mouse strains (SHN and SLN) with high and low incidences, respectively, of mammary tumors were established from the same basal stock of Swiss albino mice that were unrelated in origin to other mouse strains with mammary tumors. In the breeders, mammary tumor incidence and average age of the mice when they developed mammary tumors were 97.2 % and 6.6 months for SHN, and 5.57% and 10.1 months for SLN, respectively...