ANSC 3323 Lecture Notes - Cryoprotectant, Ice, Glycerol
Document Summary
When tissues are cooled slowly, ice forms in the extracellular space. Too much extracellular ice can cause mechanical damage to the cell membrane due to crushing: intracellular ice formation. While some organisms and tissues can tolerate some extracellular ice, any appreciable intracellular ice is almost always fatal to cells: solution effects. As ice crystals grow in freezing water, solutes are excluded, causing them to become concentrated in the remaining liquid water. High concentrations of some solutes can be very damaging: dehydration. The migration of water out of cells caused by extracellular ice formation can also cause cellular dehydration. The associated stresses on the cell can cause damage directly: when tissue is cooled below freezing, water molecules gather and form growing ice crystals. Growing ice causes cells to dehydrate and shrink: ice squeezes other molecules into harmful concentrated solution. Finally, cells are left damaged and squashed between ice crystals.
