Cryopreservation Techniques in Animal Reproductive Sciences

Cryopreservation has become integral to animal breeding, conservation and biotechnology by enabling long-term storage of gametes and embryos. Protocols typically involve controlled cooling, seeding, freezing and thawing phases, during which cells are exposed to cryoprotectants and extenders. Permeating agents such as glycerol and dimethyl sulfoxide and non-permeating compounds including sugars, amino acids or polymers act to mitigate ice-crystal formation and osmotic stress. Extenders supply nutrients, regulate pH and buffer against cold shock. Innovations in antioxidant supplementation, novel macromolecular cryoprotectants and vitrification approaches have enhanced post-thaw viability and function. Advances in imaging, molecular markers and omics technologies are refining species-specific protocols for livestock improvement, endangered species rescue and germplasm banking on a global scale.

Research from Nature Portfolio

Recent studies have explored the role of antioxidant vitamins in liquid storage of ram semen. By supplementing a Tris-citric acid-glucose extender with vitamin C, vitamin E or their combination and chilling samples at 5 °C for up to 72 hours, researchers assessed motility, viability, plasma membrane and acrosome integrity alongside computer-assisted sperm analysis parameters. The addition of either vitamin markedly improved motility indices—straight-line velocity, beat-cross frequency and path linearity—during the first 48 hours. However, overall post-storage viability and membrane stability declined similarly across treatments beyond 72 hours, indicating that antioxidant fortification can enhance short-term liquid preservation but does not extend functional lifespan under conventional cooling protocols.

Cryopreservation Techniques in Animal Reproductive Sciences publication trend

The graph below shows the total number of articles in cryopreservation techniques in animal reproductive sciences across all publications each year (not limited to Nature Index journals).

Technical terms

Cryoprotectant: A substance that protects biological cells from freeze-induced damage by reducing ice-crystal formation and osmotic stress.

Extender: A nutrient and buffer solution used to dilute and stabilise sperm or oocytes during cooling and freezing.

Vitrification: A rapid-freezing technique that solidifies cells into a glass-like state without ice-crystal formation.

Reactive Oxygen Species (ROS): Highly reactive molecules derived from oxygen that can damage lipids, proteins and DNA during cryopreservation.

Acrosome: A cap-like structure on the sperm head containing enzymes required for oocyte penetration.

Mitochondrial Membrane Potential (MMP): The electric potential difference across the mitochondrial membrane, reflecting mitochondrial health and ATP-producing capacity.

References

1. Effects of vitamins C and E in tris citric acid glucose extender on chilled semen quality of Kail ram during different storage times. Scientific Reports (2023).
2. Carboxylated ε-Poly-l-lysine Improves Post-Thaw Quality, Mitochondrial Functions and Antioxidant Defense of Goat Cryopreserved Sperm. Biology (2023).
3. Pyrroloquinoline Quinone Improves Ram Sperm Quality through Its Antioxidative Ability during Storage at 4 °C. Antioxidants (2024).
4. Cryopreservation of Semen in Domestic Animals: A Review of Current Challenges, Applications, and Prospective Strategies. Animals (2022).