Developed in 1921 by Little from brother - sister pair (57 x 52) of Miss Abby Lathrop’s stock. Strains C57BL/6 and C57BL/10 separated prior to 1937. In 1947 from Strong, Cold Spring Harbor, NY, to Kaplan, Stanford, CA, USA, to Law, National Cancer Institute, Bethesda, MD, USA
In 1965 from Law, National Cancer Institute, Bethesda, MD, USA, to Radiobiological Institute TNO, Rijswijk, The Netherlands. In 1994, to Harlan Laboratories through acquisition of ITRI-TNO, Rijswijk. Harlan was renamed Envigo in 2015.