Inbred strain Mouse
In 1921, Littel obtained mice from Lathrop and named a strain of mice that was derived from the mating of female 57 and male 52 and that consistently exhibited black hair as C57BL. The sixth subline of C57BL, i.e., C57BL/6, was introduced to the Jackson Laboratory to form the C57BL/6J strain. C57BL/6J mice were introduced from the Jackson Laboratory to NIH and were maintained as C57BL6N. C57BL/6N mice at F121 were introduced from NIH to the Central Institute for Experimental Animals in 1978, and then to CLEA Japan, Inc. at F121+25 in 1988. In addition, C57BL/6J mice at F166 were introduced from the Jackson Laboratory to CLEA Japan, Inc., in 1989, at which time their production and supply was started.
[History of cryopreservation]
C57BL/6JJcl：(1)F174(F166+8), frozen in January 1991
(2)F179(F166+13), frozen in September 1995
C57BL/6NJcl：F152(F121+25+6), frozen in July 1992
[Generation number as of August 2002]
These mice have black hair (aa BB CC DD). C57BL/6NJcl mice grow slightly better than C57BL/6JJcl mice, but there are no marked differences between the two sublines. The incidence of hair loss characteristic of the B6 strain is similar in these sublines.
These mice are known for their low incidence of mammary cancers and their resistance to exogenous tumor induction and are widely used for studies on cancer and immunology and for those in the field of toxicity and microbiology. Recently, their use as a source of embryos for developmental engineering has become common.
"This substrain is at least (a number>20 by definition) generations removed from the originating JAXR Mice strain and has NOT been re-infused with pedigreed stock from The Jackson Laboratory."