[DtheP47]

Originally Posted by Gordon Booth

If that is true how do they freeze sperm and eggs in liquid nitrogen(-196 Centigrade) but still unfreeze them and they are alive and viable?

Originally Posted by DtheP47

Think it's to do with our heads consisting of complex vegetable matter (some of us not so complex Mr B* ) Try freezing a tomato. It all turns to gooey mush when thawed out. Ice crystals form, vessels burst and fluids leak.

*Present company excepted !!

As water freezes, it expands. Since cells are made up of mostly water, freezing expands the “stuff” inside which destroys their cell walls and they die. The cryonics companies need to remove and/or replace this water. They replace it with something called a cryoprotectant. Much like the antifreeze in an car. This glycerol based mixture stops and protects against damage to your organs and tissues by hindering the formation of ice crystals. This process is called “vitrification” and allows cells to live in a sort of suspended animation.

For a tomato to remain a tomato the water would have to be removed in a process similar to the above. And then rehydrated somehow at the thawing stage.
So in essence the tomato would have to be dessicated first, ergo, you are not freezing a tomato really.