Freeze-Drying and Room Temperature Preservation of Mammalian Sperm.

Freeze-drying technology enables the safe preservation of genetic resources at room temperature, even in situations where liquid nitrogen cannot be replenished following a major disaster. In addition, genetic resource storage becomes easier, and international transport becomes possible at low cost. In addition, freeze-drying has been found to confer resistance to high temperatures and radiation, and research into the safe and permanent preservation of genetic resources outside the Earth is now underway. It has also become possible to generate cloned individuals from freeze-dried somatic cells, enabling the recovery and preservation of genetic resources even from infertile animals. However, the birth rate using freeze-dried sperm is significantly lower than that achieved with fresh sperm, and long-term storage has not yet been demonstrated. Therefore, this technology has not yet gained reliability and has not been put into practical use, although these issues are being addressed by the latest research. This chapter first provides an overview of current sperm freeze-drying methods, followed by a detailed freeze-drying protocol.