In vitro fertilization with cryopreserved inbred mouse sperm

Area of Science:

• Reproductive Biology
• Cryobiology
• Genetics

Background:

• Cryopreservation of mouse sperm is crucial for genetic resource preservation.
• Inbred mouse strains exhibit genetic variations that may affect sperm cryosurvival and fertility.

Purpose of the Study:

• To evaluate the efficacy of a specific cryopreservation protocol for mouse sperm across different inbred strains.
• To assess the impact of cryopreservation on sperm viability and fertility in C57BL/6J, DBA/2J, BALB/cJ, 129S3/SvImJ, and FVB/NJ strains.
• To identify strain-specific differences in susceptibility to cryopreservation.

Main Methods:

• Sperm from five inbred mouse strains were cryopreserved using a 3% skim milk/18% raffinose solution.
• Post-thaw sperm viability and fertility were assessed.
• Fertility was compared to fresh sperm and control B6D2F1 sperm, evaluating two-cell cleavage rates and live newborn production.

Main Results:

• The cryopreservation protocol effectively preserved sperm motility across all tested strains, with a ~50% decrease post-thaw, consistent with mammalian sperm cryopreservation.
• Significant strain-dependent differences in progressive motility and fertility were observed after thawing.
• C57BL/6J, BALB/cJ, and 129S3/SvImJ strains showed the most substantial fertility reduction, with two-cell cleavage rates dropping from 70%, 34%, and 84% to 6%, 12%, and 6%, respectively.
• Live newborns were successfully obtained from all strains using cryopreserved sperm.

Conclusions:

• The cryopreservation method is broadly applicable to different mouse inbred strains.
• Genetic background significantly influences the fertility and cryosurvival of mouse sperm.
• These findings highlight the importance of considering strain-specific characteristics when cryopreserving mouse genetic resources.