Mouse embryo culture as quality control for human in vitro fertilization: the one-cell versus the two-cell model

Female mice were superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) and mated with male mice. One-cell (n = 429) and 2-cell (n = 450) embryos were collected 20 and 42 hours after hCG and cultured in Ham's F-10 medium (Gibco, Grand Island, NY) (282 mOsm/l, pH 7.4) and in media of altered osmolality (260, 300, 316 mOsm/l), altered pH (7.0, 7.8, 8.0) or various dilutions of Cidex (Surgikos, Arlington, TX) (1:1000, 1:10,000, 1:100,000). Stages of development were observed for 4 days. The development of embryos in the 1-cell system was significantly impaired under all studied conditions by the 4-cell stage of development. The 2-cell system failed to detect trace amounts of Cidex in the culture media and an increase in osmolality to 300 mOsm/l. Other changes in osmolality (260 mOsm/l) and pH (7.8) were detected by the 2-cell system only at the blastocyst stage. The authors conclude that the 1-cell system is more sensitive than the 2-cell system to mild changes in in vitro fertilization culture media.