Culture of Ovine and Bovine Ova

Twenty-nine western ewes and six cross-bred cows were checked twice daily for estrus. The majority of animals were injected with Pregnant Mare Serum Gonadotropin (PMSG) and Human Chorionic Gonadotropin (sheep) or PMSG and Prostaglandin F2α (cow) at designated times of the estrous cycle. Ewes and cows were mated with fertile males. Laparotomies were performed to obtain 1- and 8-cell ovine embryos and 16-cell and morula stage bovine embryos. Ovine embryos were cultured from the 1-cell stage to the 8-cell stage in a balanced salt solution containing pyruvate, lactate or a combination of pyruvate and lactate. A similar salt solution with glucose as the sole carbohydrate source did not support growth of the 8-cell ovine embryo. Bovine embryos were cultured from 16-cell and morula stages to blastocyst and “hatching” in the salt solution containing α-ketoglutarate. Culture medium containing glucose as the sole carbohydrate source did not support development of 16-cell and morula stage bovine embryos. These embryos appeared to degenerate rather than split (“hatch”) as is generally reported.