The left uterine horn is punctured about 0.5 cm below the oviduct using a blunted 26-28 ga. needle. An embryo transfer pipet is introduced into this opening into the uterine lumen and the embryos expelled. The reproductive tract is replaced into the abdomen, the incision closed, and the animal treated as described for oviductal transfers. The mouse is replaced in its cage and will remove the suture with 24 hours. Pups are individually dissected from the visceral yolk sac and amnion.
Breathing is stimulated by gently pinching the body with forceps.
The foster mother should have given birth the same day or the day before. The foster mother should be removed from the cage. Cesarian derived pups can be mixed with the mother's natural pups or the natural pups can be removed.