Recovery of Preimplantation Mouse Embryos from the Oviduct and Uterus

One of the primary functions of the ovary is to produce healthy eggs for reproduction. One method to assess ovarian and defective reproductive tract function is by measuring fertilization capacity and preimplantation embryo development in the oviduct and uterus. In this study, female mice at estrus were mated overnight with a proven male, and the presence of a copulatory plug the next morning was recorded as 0.5 days post coitum (dpc). By 09:30 h on 0.5 dpc, both oviducts were dissected to isolate cumulus-oocyte complexes. Zygotes were identified at the pronuclear stage. The oviducts were then excised at 1.5 dpc and 2.5 dpc to retrieve 2-cell and 4- to 8-cell embryos using a blunted 30-G needle filled with Leibovitz-15 medium plus 1% fetal bovine serum. At 3.5 dpc, both the oviduct and uterus were flushed for morula and blastocyst stage embryos. The total number of fertilized eggs and embryos at each stage can be expressed as a percentage of the total ovulated eggs, serving as indicators of egg competency.