How much does a mouse brain weigh? - briefly
A typical laboratory mouse brain weighs roughly 0.4 g (about 400 mg). Weight varies with strain and age, generally falling between 0.3 g and 0.5 g.
How much does a mouse brain weigh? - in detail
The average adult laboratory mouse (Mus musculus) possesses a brain that weighs approximately 0.4 g to 0.5 g. This value represents the combined mass of gray and white matter, vasculature, and cerebrospinal fluid. Several factors influence the precise measurement:
- Strain differences – Inbred strains such as C57BL/6 tend toward the lower end of the range, while larger outbred strains may approach 0.6 g.
- Sex – Male mice generally have slightly heavier brains than females, reflecting overall body size differences.
- Age – Brain mass peaks around 8–12 weeks of age; younger pups have considerably lighter brains, and senescent animals may exhibit slight reductions due to neurodegeneration.
- Nutritional status – Caloric restriction or malnutrition can reduce brain weight, whereas overnutrition may increase it modestly.
Measurement techniques typically involve rapid dissection followed by weighing with an analytical balance of at least 0.01 g precision. To avoid dehydration artifacts, brains are weighed fresh or after brief fixation in isotonic solutions.
Comparatively, the mouse brain constitutes roughly 0.5 % of total body mass, a proportion similar to that observed in many small mammals. This small absolute weight poses challenges for neuroanatomical studies but also enables high‑throughput experimental designs.