Vitrification is a form of cryopreservation in which a biological sample, in IVF this is usually an embryo or egg, is cooled so rapidly that the water in and around the cells transforms into a glass-like amorphous solid rather than forming ice crystals. The name comes from the Latin word for glass, vitrum.
The reason ice crystal formation is so damaging is mechanical. Ice crystals have sharp edges and significant volume. As they form inside or between cells, they physically rupture cell membranes and destroy the cellular architecture necessary for normal function after thawing. Slow freezing, the older method, could reduce crystal formation through careful use of cryoprotectant chemicals and controlled cooling rates, but could never eliminate it entirely.
Vitrification eliminates it by removing the opportunity for crystals to form at all. The embryo is loaded onto a carrier device with a very small volume of highly concentrated cryoprotectant solution, then plunged directly into liquid nitrogen at minus 196 degrees Celsius. The cooling rate, often 20,000 degrees Celsius per minute or faster, is so extreme that the cellular fluid transitions directly from a liquid state to a solid glass-like state without passing through the crystallisation range.
The clinical impact on UK IVF has been transformative. Embryo survival rates with vitrification routinely exceed 90 percent in well-run laboratories, compared to 70 to 80 percent for slow-frozen embryos. Frozen embryo transfer success rates at many UK clinics now match or exceed those of fresh transfers. This has enabled widespread adoption of freeze-all strategies, where all embryos from a stimulation cycle are cryopreserved for transfer in subsequent natural or medicated cycles.
For UK fertility clinics sourcing vitrification equipment, carrier devices, and supporting cryogenic storage, Cryolab provides the full range of products with expert consultation at https://cryolab.co.uk
