How long is a mouse's gestation period? - briefly
The gestation lasts approximately 19–21 days. Slight variations occur depending on strain and housing conditions.
How long is a mouse's gestation period? - in detail
The pregnancy of a common laboratory mouse lasts approximately 19 to 21 days from conception to birth. This interval is consistent across most strains of Mus musculus, although slight deviations occur with different genetic lines or environmental conditions.
Key factors that can modify the timeline include:
- Ambient temperature: cooler environments may extend gestation by 1–2 days, while optimal temperatures (22–24 °C) keep the period at the standard range.
- Maternal nutrition: protein‑deficient diets can lengthen gestation and increase embryonic mortality.
- Strain differences: some inbred lines (e.g., C57BL/6) exhibit a median of 20 days, whereas outbred stocks may average 19 days.
During the gestational window, embryonic development follows a predictable sequence:
- Days 1‑3: fertilization and early cleavage; blastocyst implantation in the uterine lining.
- Days 4‑7: formation of the primitive streak, beginning of organogenesis.
- Days 8‑12: rapid growth of the central nervous system, limb buds appear.
- Days 13‑16: differentiation of major organs, development of hair follicles and whiskers.
- Days 17‑21: maturation of lungs, preparation for parturition; pups gain body mass and acquire fur.
Mice typically deliver litters of 5–8 pups, though numbers can range from 1 to over 12 depending on strain and maternal condition. The short gestational period, combined with a rapid estrous cycle (4–5 days) and early sexual maturity (6–8 weeks), enables high reproductive turnover, which is why mice serve as a standard model in biomedical research.