Why are lab mice white? - briefly
Laboratory mice are bred to be albino because the lack of pigment simplifies visual assessment of physiological changes and genetic modifications, and the uniform coat reduces variability in experiments. Albino strains also have a well‑characterized genome and are readily available from established colonies.
Why are lab mice white? - in detail
Laboratory mice are predominantly white because a recessive mutation in the tyrosinase gene eliminates melanin production, resulting in an albino phenotype. The mutation is homozygous in most standard strains, ensuring a uniform coat color across generations.
The albino condition offers several practical benefits:
- High contrast against typical bedding and equipment, facilitating visual inspection for injuries, tumors, or abnormal behavior.
- Compatibility with optical imaging techniques; lack of pigment reduces light absorption and scattering, improving fluorescence and bioluminescence signal detection.
- Simplified genetic monitoring; coat color serves as an immediate phenotypic marker for genotype verification and colony management.
- Reduced variability in experiments that involve skin or eye physiology, as pigment can interfere with drug absorption or ocular studies.
The first albino mouse strain, derived in the early 1900s, was deliberately selected for its conspicuous appearance and ease of handling. Subsequent inbreeding produced highly isogenic lines such as BALB/c and Swiss Webster, which retain the white coat while offering consistent genetic backgrounds. Routine breeding protocols maintain homozygosity for the tyrosinase mutation, preventing reintroduction of pigmentation.
Although white mice dominate many facilities, researchers employ pigmented strains when melanin‑related pathways are under investigation or when coat color might affect specific outcomes. The choice of coat color therefore reflects a balance between experimental requirements and the logistical advantages conferred by albinism.