Effect of storage temperature on sperm cryopreservation

Area of Science:

• Andrology and reproductive medicine
• Cryobiology
• Sperm cryopreservation techniques

Background:

• Sperm cryopreservation is crucial for assisted reproductive technologies.
• Optimal temperature for long-term sperm storage remains an area of investigation.
• Previous studies have not definitively compared -70°C and -196°C for sperm preservation.

Purpose of the Study:

• To investigate the effect of different cryopreservation temperatures on human sperm quality.
• To compare the viability of sperm stored at -70°C versus -196°C.
• To assess the impact of cryopreservation duration on sperm motility and morphology.

Main Methods:

• A controlled, blinded study was conducted in an andrology laboratory.
• Sixteen semen samples from men with normal fertility parameters were used.
• Sperm aliquots were cryopreserved at -70°C or -196°C for 7 days or 3 months using a programmable freezer and test yolk buffer.

Main Results:

• Sperm motility decreased significantly more at -70°C compared to -196°C after 7 days (47% vs. 39% decrease).
• The difference in motility loss was more pronounced after 3 months, with a 72% decrease at -70°C versus 39% at -196°C.
• No significant differences in post-thaw sperm morphology were observed between the two temperatures.

Conclusions:

• Cryopreservation at -196°C (liquid nitrogen) is superior for maintaining human sperm motility compared to -70°C.
• -70°C may be suitable for short-term sperm storage with acceptable motility preservation.
• Sperm morphology is not significantly affected by cryopreservation temperature within the tested parameters.