The aim of this brief report is to offer a solution for a problem that compromises the quality of in vitro-produced mammalian embryos. The harmful effects of evaporation-induced osmotic changes in mammalian embryo cultures have been recognized only recently. In this technical report, we describe a modified embryo culture dish (Humdish) that provides consistent >97% humidity and fully eliminates osmotic changes in the commonly used drop-under-oil culture systems from day 0 to 6. As an additional benefit, the Humdish also increases the temperature stability of cultures. If subsequent laboratory and clinical experiments prove its value, our suggested approach may help to improve the in vitro environment and quality of all preimplantation stage mammalian embryos, including the most sensitive ones produced from artificial gametes or by somatic cell nuclear transfer.
Keywords: embryo culture; evaporation; humidity; osmolality.