The critical storage threshold for cryopreserved embryos is approximately -130°C. Below this temperature, embryos enter the glassy (vitreous) state in which ice crystal formation is arrested and biological time effectively stops. This is the temperature at which the physical state of the cell transitions from a supercooled liquid to an amorphous solid — a point sometimes referred to as the glass transition temperature. Above -130°C, even briefly, biological activity can resume and cellular damage from ice crystal formation or enzymatic activity becomes possible.
This threshold is the number that matters operationally, not the boiling point of liquid nitrogen at -195.8°C. The boiling point tells you the temperature of the liquid itself at atmospheric pressure. The storage threshold tells you the minimum your vessel must maintain around your samples at all times, including when the fill level is low, when ambient temperature is elevated, or when a liquid nitrogen delivery is overdue.
CryoNest vapour phase storage maintains samples between -150°C and -190°C — a significant margin below -130°C when correctly filled. The static evaporation rate of the vessel determines how quickly that margin narrows between top-ups. HFEA licence conditions require continuous temperature monitoring with alarm thresholds set below -130°C for all regulated embryo storage. For storage vessel selection based on your specific holding requirements, contact Cryolab.
