How many cells does a mouse have? - briefly
A typical laboratory mouse possesses on the order of 10 billion somatic cells. This estimate reflects its body mass of roughly 20–25 grams compared with larger mammals.
How many cells does a mouse have? - in detail
A typical laboratory mouse contains on the order of 10 billion to 30 billion individual cells. This estimate results from combining measured cell densities for major tissues with the average organ masses of a 20–25 g adult mouse.
- Blood: Red blood cells dominate the circulatory system. Approximately 1 × 10⁹ erythrocytes reside in the mouse bloodstream, based on a hematocrit of ~45 % and a total blood volume of ~1.5 mL.
- Muscle: Skeletal muscle accounts for roughly 40 % of body mass. Histological counts give about 5 × 10⁹ muscle fibers, each containing multiple nuclei; the total nuclear count in muscle tissue reaches ≈1 × 10¹⁰.
- Liver: Hepatocytes represent the primary cell type in the liver, which weighs ~1.5 g. Cell density measurements indicate ≈2 × 10⁸ hepatocytes.
- Skin: The epidermis and dermis together contain ≈1 × 10⁹ keratinocytes and fibroblasts.
- Brain: Neuronal and glial populations sum to ≈1 × 10⁸ cells, reflecting the small brain mass (~0.4 g).
- Adipose tissue: Adipocytes contribute ≈5 × 10⁸ cells, consistent with a fat depot of ~1 g.
- Other organs (kidney, spleen, heart, etc.): Combined cell counts for these structures add another ≈1 × 10⁹ cells.
Summing the contributions yields a total cell number between 1 × 10¹⁰ and 3 × 10¹⁰. Variability arises from genetic strain, age, sex, and physiological state, which affect organ size and cellular composition. The quoted range therefore represents a robust approximation for a healthy adult mouse.