Vendors of genetically modified rodents U of M Mouse Manipulative Genetics Laboratory - services include consultation on breeding colony management and experimental design, creation of homologous recombintation and transgenic mice, rederivation of mouse lines. Its naturally high fecundity can be utilized successfully, but it can also be a source of frustration when controlled reproduction is desired. The mouse reaches sexual maturity by six weeks of age and litter mates must be separated by this time to prevent inadvertent inbreeding. The female is polyestrus, with the estrus lasting 4-5 days. The length of estrus can vary considerably depending on a number of factors.
Males are able to breed at any time after puberty.
Estrus can be detected by performing a vaginal swab or lavage and examining cells microscopically. There is an increasing population of cornified squamous epithelial cells with pyknotic nuclei, as the animal approaches estrus. Leukocytes gradually infiltrate during diestrus. Anestrous is characterized by non-cornified epithelial cells. Red blood cells are not prominent during proestrus as in the canine.