How many chromosomes does a mouse somatic cell have? - briefly
A mouse somatic cell carries 40 chromosomes, organized as 20 homologous pairs. This diploid number is consistent across all non‑reproductive cells of the species.
How many chromosomes does a mouse somatic cell have? - in detail
Mouse somatic cells contain a diploid set of 40 chromosomes, arranged in 20 homologous pairs.
The complement consists of 38 autosomes and a pair of sex chromosomes. In females the sex pair is XX; in males it is XY. Each autosomal pair is numbered 1 through 19 based on size and banding pattern, with chromosome 1 being the largest.
All nucleated tissues of a laboratory mouse share this chromosome number. Only the gametes differ, carrying a haploid complement of 20 chromosomes (19 autosomes plus one sex chromosome). The standard karyotype for common inbred strains, such as C57BL/6, matches the 40‑chromosome count without structural rearrangements.
Key points:
- Total chromosomes: 40 (2 × 20)
- Autosomes: 38 (19 pairs)
- Sex chromosomes: 2 (XX or XY)
- Uniform across somatic cell types
- Haploid gametes: 20 chromosomes
- Minor variations may arise from spontaneous aneuploidy or engineered chromosomal alterations
The chromosome number is determined by conventional cytogenetic techniques, including G‑banding and fluorescence in situ hybridization, which confirm the consistent diploid complement in mouse somatic cells.