At room temperature, water molecules are arranged randomly and can mingle with other molecules. When the water freezes, however, its molecules align themselves in a pure-water rigid structure. This means that when ice forms inside tissue, the vital ions and proteins of the tissue are forced into the shrinking pockets of residual unfrozen water. Even the fabric of cells themselves is crushed into these tiny spaces among the ice crystals. As cooling continues, more than eighty percent of tissue volume can become converted to ice, and the cells are crushed beyond recovery.
Vitrification eliminates the formation of ice during cooling.
If the vitrification solution readily permeates the cells, vitrification is a way of stopping biological time without disturbing the natural order inside living cells. As a result, liquid water molecules remain mixed with other chemicals during deep cooling, instead of coming out of solution into a pure water-ice phase. There is no disturbance of other chemicals or cell components. Everything stays in its correct physiological place as cooling proceeds. Modest concentrations of a cryoprotectant such as glycerol are used to protect cells during freezing by reducing the amount of ice that forms.