Strain Means

Standard Inbred Mice

These are genetically homozygous and fully inbred strains. Variation within an inbred strain is due to environmental effects and developmental noise. No systematic effort was taken to minimize environmental differences. Animals are of mixed sexes and ages.

F1 Inbred Mice

The F1 hybrids are heterozygous at many gene loci, but members of a given cross are also genetically identical. Consequently, variation among members of a particular cross is environmental in origin. The F1's were generated by a cross between a low and a high cell number strain. The MidPar column is the midpoint between the low and the high strain. Maternal effect can be assessed by comparing reciprocal F1 crosses.

Recombinant Inbred Strains

Recombinant inbred strains are often used for mapping QTLs. We have strain data for two RI sets, BXD and BXH. The BXD set was generated from an outcross between the parental strains C57BL/6J and DBA/2J, and the BXH set was generated from an outcross between C3H and DBA/2J.

Genetically Heterogeneous Strains

These are outcrossed or randomly-bred strains of mice. Variation in these strains is primarily the sum of environmental factors and genetic differences.

Wild Inbred Strains

These are inbred strains of mice derived from several different species of mice. Standard inbred mice were probably derived from a cross between Mus domesticus and Mus molossinus. The lineages of some of these species diverged more than 2 million years ago.

Interspecies F1, F2, and N2 backcross progeny

Interspecies crosses are often used to estimate numbers of genes affecting a quantitative trait and in mapping genes and QTLs. We have crossed CAST/Ei with BALB/c.

Abbreviations used in tables:

Summary Data on the Retinal Ganglion Cell Population in Strains of Mice