In the oviduct transfer, microinjected embryos are implanted into the ampulla of recipient pseudopregnant females. It is preferably performed on the same day as the microinjections to minimize the time the injected eggs are in culture. Alternatively, it can be performed on the following day when it is possible to observe if the injected eggs have developed to the two cell stage. Fifteen to 20 eggs delivered to each oviduct (30-40 eggs overall) should give an ideal litter size of 5-10 pups. In practice, the number of eggs needed to achieve this number depends on the competence of the experimenter. Oviduct transfer is not an easy technique, and novice experimenters are advised to practice with cadavers until they are happy with the procedure. A convenient dye can be used in place of eggs to visualize correct delivery of the pipet contents into the ampulla.
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