Karyotype of NIH, C57BL/6 and Razi strains of laboratory mice (Mus musculus)

The laboratory mouse is recognized as the pre-eminent model for genetic research. Awareness of chromosomal patterns of experimental animals increases their value for a variety of different fields of study. We aimed to study mitotic chromosome preparations from NIH, C57BL/6 and Razi strains of mice, which are outbred, inbred and partially inbred laboratory mice respectively. Bone marrow cells were prepared from 36 male and female mice, 12 from each strain, and stained by use of Giemsa staining and G-banding methods. Karyotyping of the samples showed that there was no difference in chromosomal numbers among the three mice strains, also the metaphase preparations of their diploid cells contained 40 chromosomes (2n = 40) and all chromosomes were telocentric. However, some differences in band tonality and the size of chromosomes were seen.