Principles of Genetics and Breeding

9.1.7.6 Thawing

• Cooling and thawing rates are among the most critical variables affecting the success of cryopreservation.
• In case of carps spermatozoa fast thawing is preferable as slow thawing can recrystalize the small inter cellular crystals which may damage the cells.
• The cryomilt samples of carps can be thawed in warm water of 38+1ºC for 7-9 secs.
• Sperm motility should be estimated.
• Qualitative observations of thawed sperm can be quite helpful in evaluating protocols.
• For example, if the sperm cells are visibly damaged, the cryoprotectant concentration may have been too low, or the cooling rate may have been too rapid. Conversely, if the cell morphology is intact although the sperm are immotile, the concentration of the cryoprotectant may have been too high. This would be confirmed by a reduction in the equilibration motility.