At what age does a mouse reach sexual maturity? - briefly
Laboratory mice reach sexual maturity at approximately 5–6 weeks of age; females typically exhibit estrus by six weeks, while males begin producing viable sperm around five weeks.
At what age does a mouse reach sexual maturity? - in detail
Mice typically attain reproductive capability between five and six weeks of age, although the precise timing varies among strains and sexes. In laboratory strains such as C57BL/6, females usually exhibit vaginal opening at 4–5 weeks, followed by first estrus within a few days; males show preputial separation at a comparable age and begin producing sperm shortly thereafter. Hormonal surges—rise in luteinizing hormone, follicle‑stimulating hormone, and gonadal steroids—drive these morphological changes.
Key indicators of sexual maturity:
- Vaginal opening (females)
- First estrus cycle (females)
- Preputial separation (males)
- Presence of mature spermatozoa in epididymis (males)
Factors influencing the onset include:
- Genetic background (different inbred lines mature at slightly different ages)
- Nutrition (adequate protein and caloric intake accelerates development)
- Photoperiod and ambient temperature (extreme conditions can delay puberty)
- Social environment (group housing may affect hormonal regulation)
In summary, most mice become reproductively competent around the fifth to sixth week post‑natal, with observable physical markers and hormonal profiles confirming maturity. Adjustments in husbandry or experimental design should account for this developmental window to ensure accurate timing of reproductive studies.