Our docs want us to vitrify but we like slow-cooling

No problem. Slow-cooling is vitrification! You are already vitrifying your patient's embryos.

There is no reason to switch to a vitrification protocol if you have good success slow-cooling. By good success we mean at least 90% survival, and pregnancy rates that are within 5-10% of your clinics pregnancy rates with fresh embryos. If your rates are good, and you continue to slow-cool, you can correctly tell your patients you are vitrifying their cells. If your rates are not this good then you may want to look into testing a rapid-cooling vitrification system out. Check out the ICE Vitrification system page for more details.

Vitrification has nothing to do with the rate of cooling. It is the ability of a solution to solidify in an amorphous state, without crystal formation. This happens in rapid-cooling as well as slow-cooling.

During slow-cooling, the temperature is slowly reduced to -35C before plunging into liquid nitrogen. At -35C, there is some ice in the solution surrounding your cells because you "seeded" the straw, however the cells and most of the solution is still in liquid form. When you plunge in liquid nitrogen, the cells and remainding liquid vitrifies. It has to, otherwise your cells would all die upon warming; and this does not happen. Please contact us for any questions you may have regarding this.