How many chromosomes does a mouse somatic cell contain? - briefly
A mouse somatic cell possesses 40 chromosomes, arranged in 20 homologous pairs.
How many chromosomes does a mouse somatic cell contain? - in detail
Mouse somatic cells are diploid, containing forty chromosomes in total (2 n = 40). The complement consists of thirty‑eight autosomes arranged in nineteen homologous pairs and two sex chromosomes, either an X‑X pair in females or an X‑Y pair in males. Each autosomal pair includes a metacentric, submetacentric or acrocentric chromosome, reflecting the typical Mus musculus karyotype.
- Autosomes: 19 pairs (38 chromosomes)
- Sex chromosomes: 1 pair (2 chromosomes) – XX in females, XY in males
Chromosome number is established during mitosis, where sister chromatids separate so that each daughter cell receives one complete set. Techniques for determining the count include G‑banding of metaphase spreads, fluorescence in situ hybridisation (FISH) with chromosome‑specific probes, and flow cytometry of isolated nuclei. Standard laboratory mouse strains (e.g., C57BL/6, BALB/c) consistently display the 40‑chromosome complement, while some wild‑derived or genetically engineered lines may exhibit aneuploidies or translocations that alter the nominal count.
The mouse genome is organized into approximately 2.7 gigabases, with each chromosome ranging from about 70 megabases (smallest) to over 200 megabases (largest). Gene density, repetitive elements, and centromere position vary among chromosomes, influencing both cytogenetic identification and functional studies. Knowledge of the exact chromosome complement underpins experimental design, genetic mapping, and interpretation of phenotypic outcomes in mouse models.