When does a mouse become an adult? - briefly
Mice attain sexual maturity at roughly five to six weeks of age, and are generally classified as adults by eight weeks. This developmental stage marks the transition from juvenile growth to reproductive capability.
When does a mouse become an adult? - in detail
Mice reach adulthood through a series of physiological milestones that occur within the first two months of life.
Gestation lasts 19–21 days, after which newborns are altricial and dependent on maternal care.
Weaning typically occurs at 21–28 days, marking the end of nursing and the beginning of independent feeding.
Sexual maturity follows:
- Females attain first estrus between 5 and 7 weeks; regular estrous cycles commence thereafter.
- Males exhibit sperm production and testicular enlargement around 6–8 weeks; mating behavior emerges at this stage.
Physical indicators of adult status include:
- Body weight exceeding 20 g for most laboratory strains.
- Full development of secondary sexual characteristics: scrotal descent in males, mammary gland maturation in females.
- Stabilization of growth rate; skeletal length reaches adult dimensions.
Variability arises from genetic background, diet, and housing conditions. Certain inbred strains mature slightly earlier, while outbred populations may require up to 10 weeks for complete reproductive competence.
In research contexts, the age of 8 weeks is commonly adopted as the standard definition of adult mouse, providing a consistent reference point for experimental design.