Mammalian preimplantation embryo culture.

Since the inception of modern embryo culture media over 50 years ago there have been significant developments in culture systems for the mammalian preimplantation embryo. Carbohydrate gradients have been shown to impact embryo physiology and viability, while amino acids have been determined to have specific temporal effects during the preimplantation period. Furthermore, due to the lability of amino acids at 37 °C and the subsequent release of embryo-toxic ammonium into the medium, the medium is renewed every 48 h not only to provide stage-specific nutrients but also to prevent toxicity. Subsequently stage-specific media are commonly employed. To facilitate the preparation of small volumes of media, whose formulations can be readily altered according to experimental design, the use of stock solutions is described, together with systems to facilitate the development of viable embryos.