Evolution of a culture protocol for successful blastocyst development and pregnancy

Abstract

A cell-free culture system was designed for human embryo development to the blastocyst stage by testing a range of culture conditions in a series of protocols. The culture system that was evolved has a brief 1 h exposure to spermatozoa and then culture of the pronucleate zygote for 2 days in IVF-50 medium. Two or three embryos were cultured together in 20 μ1 microdrops of medium under oil. Embryos were then regrouped and two or three at a similar stage were cultured together in 50 μ1 microdrops of Gardner's G2 medium under oil from days 3 to 5. Embryos were transferred to fresh G2 medium on day 5 and cultured for a further 1 or 2 days (day 6 or 7). No serum was used in any of the cultures. T..