1. Sexual Maturity: Mice reach sexual maturity at around 6-8 weeks of age. Males and females both become capable of reproducing at this stage.
2. Estrus Cycle in Females: Female mice have an estrus cycle, which is the reproductive cycle. This cycle involves periods of estrus (receptivity to mating) and diestrus (non-receptive phase). The estrus cycle lasts around 4-5 days in mice and is regulated by hormones.
3. Courtship and Mating: During estrus, female mice release chemical signals (pheromones) through urine and other scent markings. These pheromones attract males and trigger courtship behavior. Male mice will sniff and chase the female, groom her, and display mating postures. Mating occurs when the male mounts the female and inserts his penis into her vagina.
4. Gestation: If mating is successful, the female mouse becomes pregnant and enters the gestation period. The gestation period in mice is relatively short, lasting around 20-22 days. During this time, the fertilized eggs develop into embryos and implant into the uterine lining.
5. Litter Size: Female mice typically give birth to a litter of 6-12 offspring, although larger litters are not uncommon. Pups are born altricial, meaning they are helpless and underdeveloped at birth. They rely on their mother for nourishment, warmth, and protection.
6. Lactation and Weaning: After giving birth, female mice produce milk to nurse their pups. The lactation period lasts for about 3 weeks, during which time the pups grow rapidly and develop fur, eyes open, and begin to explore their surroundings. Around 3-4 weeks of age, pups are weaned and start to eat solid food.
7. Postpartum Estrus: Female mice can experience postpartum estrus shortly after giving birth. This means they may become fertile again while still nursing their current litter.
Breeding pairs or colonies of mice are often kept in laboratory settings for research or breeding purposes. Genetic strains and specific characteristics can be selectively bred to study different aspects of biology, genetics, and disease models in mice.