Human preimplantation embryo culture media: past, present, and future

Systematic studies of mouse embryo culture beginning in 1949 led to an understanding of essential medium components for early mammalian embryos, and embryo culture from the zygote to the blastocyst stage was achieved in 1968. Since then, medium components that are either beneficial or detrimental for embryo culture have been identified. A variety of culture media that mimic the female reproductive tract, such as human tubal fluid medium and sequential media, were developed from the 1970s to the 1990s, and a single medium in which the concentrations of components were determined by a simplex optimization method was introduced for clinical use in 2002. While either sequential media or a single medium is currently used in most cases, no conclusion has yet been reached as to which of the two approaches is the best. That we are now easily able to culture embryos is the result of the work of pioneers. This review presents a chronological overview of media development from initial attempts at mouse embryo culture using synthetic media to the human embryo culture media used today. It also presents the characteristics of sequential media and a single medium. Finally, problems observed with current embryo culture media are discussed, along with future development in this area.