The invention involves immersing a mammalian tissue or cultured tissue equivalent in a cryoprotectant solution, agitating the cryoprotectant solution and the immersed tissue to achieve {HEAD ~ effective penetration} of {TAIL ~ the cryoprotectant solution} into the tissue, and then freezing the tissue at a very slow freezing rate at 0.3° C. or less/min 
The invention involves immersing a mammalian tissue or cultured tissue equivalent in a cryoprotectant solution , agitating the cryoprotectant solution and the immersed tissue to achieve { HEAD ~ effective penetration } of { TAIL ~ the cryoprotectant solution } into the tissue , and then freezing the tissue at a very slow freezing rate at 0.3 ° C. or less / min
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