Freeze Drying as a Method of Long-Term Conservation of Mammalian Semen – A Review

Abstract

With the development of biotechnological methods that allow for the manipulation and free exchange of genetic material, there is a need to improve the methods of collecting and storing such material. Until now, freezing in liquid nitrogen has allowed the storage of cells and entire plant and animal tissues for practically unlimited time. Despite this, alternatives are still being sought that will eliminate the constant need to keep samples at low temperature. Lyophilization or freeze drying can be an alternative to standard freezing procedures. The storage of samples (lyophilisates) does not require specialized equipment but only the refinement of the preservation method itself. In the case of cells capable of movement, e.g. sperm, as a result of the lyophilization process, they lose the ability to reach the oocyte in vivo and IVF. However, it is possible to use freeze-dried sperm for in vitro fertilization by ICSI, which is observed on the basis of the results obtained in cleavage, embryo development and production of live born offspring after embryo transfer. Studies on lyophilization of sperm are carried out on many animal species, both laboratory and livestock. This conservation method is seen as the possibility of creating biobanking for genetically valuable and endangered species with the simultaneous application of ICSI. This review article was intended to present the issues of the freeze-drying process of mammalian semen and help in finding solutions that will improve this technique of long-term preservation of biological material.