Transgenic Core Facility

Breeding Positive Transgenic Founder Mice

Mice usually will not breed if they are younger than 4 weeks of age or older than 6 or 8 months of age. If the founder mouse is male, set it up with two female mice. Female mice should be placed in the male’s cage. Placing a male into a female’s cage may result in the male killing the female. Place the male into a separate cage a week in advance of mating, if possible, and then introduce the female into the cage. If the founder is a female, then introduce her into a cage with a single male. Check the next day to see if the animals are fighting. Animals may need to be separated if that is the case. Gestation for mice is approximately 20 days. Separate the pregnant female from the male prior to birth of the offspring.

To maintain a transgenic mouse line, it is recommended that you breed animals occasionally prior to six months of age.