F1 hybrids are the first generation of a cross between two inbred strains. They have many of the useful features of inbred strains, but also tend to be more vigorous and less sensitive to adverse environmental conditions. Many characteristics of these F1 hybrid strains (particularly those with a polygenetic mode of inheritance) will be intermediate between the parental strains. F1 hybrid strains should not normally be used for breeding, as their offspring will show genetic segregation for the loci at which the parental strains differed. Two individuals of the same F1 hybrid cross will be genetically identical and will accept reciprocal skin grafts. Such F1 hybrids will also accept grafts of skin, cells and tumours from either parental strain, though the converse is not true. The characteristics of F1 hybrids are usually less well documented than those of inbred strains, although there are some important exceptions.

ORIGIN: A cross between female BALB/c and male DBA/2.
COAT COLOR: Brown
RESEARCH APPLICATION: safety and efficacy testing, transplantation research, monoclonal antibody production

CB6F1 Mouse, Nomenclature CB6F1/Crl

ORIGIN: A cross between female BALB/c and male C57BL/6
COAT COLOR: Agouti
RESEARCH APPLICATION: transplantation research, monoclonal antibody production

B6C3F1 Mouse, Nomenclature B6C3F1/Crl

ORIGIN: A cross between female C57BL/6 and male C3H.
COAT COLOR: Agouti (wild-type)
RESEARCH APPLICATION: safety and efficacy testing, transgenic/knockout model development, transplantation research

B6D2F1 (BDF1) Mouse, Nomenclature B6D2F1/Crl