What is the gestation period for mice? - briefly
Mice typically gestate for 19–21 days before parturition. Slight variations occur among strains and under different environmental conditions.
What is the gestation period for mice? - in detail
The gestation of house mice (Mus musculus) lasts approximately 19–21 days, with 20 days representing the median across most laboratory strains. This interval is measured from the detection of a vaginal plug to the birth of viable pups.
Key variables influencing the exact duration include:
- Strain genetics: Inbred lines such as C57BL/6 tend toward the lower end of the range (≈19 days), whereas outbred stocks may extend to 21 days.
- Maternal age: Younger females (<8 weeks) often experience slightly shorter pregnancies; older dams (>30 weeks) may show modest prolongation.
- Environmental conditions: Ambient temperature below 20 °C or above 30 °C can delay parturition by 1–2 days; consistent lighting cycles help maintain the standard timeline.
- Nutritional status: Caloric restriction or severe protein deficiency can lengthen gestation, while excess nutrition has minimal effect.
During the 20‑day period, embryonic development proceeds through well‑defined stages:
- Days 1–3: Implantation of the blastocyst into the uterine wall; formation of the embryonic disc.
- Days 4–7: Organogenesis begins; limb buds appear; primary heart tube initiates beating.
- Days 8–12: Growth of major organs; sensory structures (eyes, ears) become recognizable.
- Days 13–16: Rapid somatic growth; fur development; fetal movement detectable.
- Days 17–20: Final maturation of lungs, brain, and reproductive systems; preparation for parturition.
The short gestational length enables mice to produce multiple litters annually, typically 5–10 pups per litter. This rapid reproductive cycle underpins their widespread use in genetic and biomedical research, where precise timing of embryonic stages is critical for experimental design.