Flushing the oviduct and uterus is commonly used to collect 8-cell embryos from mice. But it takes lots of practice and is time-consuming. After ovulation, the early embryos travel down from the oviduct to uterus. At e0.5, they are in oviduct and travel down gradually and at e2.5, they reach to the junction of the oviduct and uterus. At e3.5, they reach to the uterus. Based on that, we find another way to collect 8-cell stage embryos. It is easier to learn and time-efficient. Collected morulaes can be used for ESc microinjection and other applications, e.g. embryo cryopreservation. We use this protocol successfully to get large number of embryos for ES microinjection.
Pregnant female mice (dpc2.5): C57B6J, age 3 to 5 weeks old, superovulated, housed at barrier facility