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 Another approach is to replace permeable CPAs with non-permeable CPAs (such as carbohydrates, proteins and other extracellular agents) to minimize osmotic shock by decreasing osmotic pressure and stabilizing the nuclear membrane
Non-penetrating CPAs possess a unique property : stabilization of a cell membrane
The high viscosity of the sperm cytoplasm due to large amounts of proteins, nucleotides, sugars and low water in human spermatozoa content (~ 50%) determines the ability of human sperm to be vitrified using protein and sugar-rich non-penetrating agents (Koshimoto et al., 2000)
KOSHIMOTO ET AL. 2000 / 19
‘Vitrification’ of spermatozoa ?
 It has been demonstrated that under all cooling rates (-1°C/min to -3000 °C/min) spermatozoa do not
contain intracellular ice, so vitrification of the intracellular compartment always occurs
 Cell damage to spermatozoa is a result of an osmotic imbalance encountered during thawing due to limited ice crystallisation in the extracellular fluid
 Most of the studies used small volumes to achieve ultra rapid cooling also allows vitrifcation of the extracellular medium
 Very rapid warming would minimise cell damage due to devitrification of the suspending medium during warming
MORRIS ET AL. , 2012 / 20
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