Mice, Congenic: Mouse strains constructed to possess identical genotypes except for a difference at a single gene locus.Animals, Congenic: Animals that are produced through selective breeding to eliminate genetic background differences except for a single or few specific loci. They are used to investigate the contribution of genetic background differences to PHENOTYPE.Mice, Inbred C57BLMice, Inbred NOD: A strain of non-obese diabetic mice developed in Japan that has been widely studied as a model for T-cell-dependent autoimmune insulin-dependent diabetes mellitus in which insulitis is a major histopathologic feature, and in which genetic susceptibility is strongly MHC-linked.Chromosomes, Mammalian: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of MAMMALS.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Quantitative Trait Loci: Genetic loci associated with a QUANTITATIVE TRAIT.Chromosome Mapping: Any method used for determining the location of and relative distances between genes on a chromosome.Mice, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.Rats, Inbred Dahl: Inbred rats derived from Sprague-Dawley rats and used for the study of salt-dependent hypertension. Salt-sensitive and salt-resistant strains have been selectively bred to show the opposite genetically determined blood pressure responses to excess sodium chloride ingestion.