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Cryodamage in spermatozoa
1. Effectofcryoprotectant
• High concentrations of glycerol have toxic effects on mitochondria
• Inappropriate concentrations of CPAs can cause intracellular and extracellular ice formation
2. Extracelluariceformation
• Extracellular ice formation in the cryosolution surrounding the spematozoa can cause mechanical
damage to the cell membrane due to crushing
3. Osmoticimbalance
• With their high proportion of membrane lipids, sperm is very sensitive to osmotic changes and lethal injury
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Cryodamage in spermatozoa
4. Hypothermic injury
• ‘Cold shock’ : sperm plasma is the primary site of cooling damage. Lipid phase transitions of
plasma membrane may cause irreparable injury even after cells return to physiologic temperatures. Hypothermia affects membrane lipid composition, plasma membrane proteins and cytoplasmic Ca2+ level
5. cryopreservation increases premature capacitation of spermatozoa
6. Cryopreservation and thawing is associated with increased ROS production
7. Cryopreservation alters mitochondrial membrane fluidity which leads to rise in mitochondrial membrane potential and the release of ROS : excessive production of ROS has been associated with loss of sperm motility
Vitrification in Assisted Reproduction : A Userʼs Manual 2015
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PRECONGRESS COURSE 11 I BARCELONA, SPAIN – 1 JULY 2018 53