Cryoprotectant Substances Used in Sperm Processing and Cryopreservation Methods

Abstract

Reproduction biotechnology is of great importance in the field of animal husbandry. Biotechnology provides application opportunities in many fields, especially artificial insemination. The most common biotechnology method is the freezing of valuable male gamete cells and then artificial insemination. While genetic breeding can be achieved in the desired direction with artificial insemination, unnecessary male breeder feeding burden is avoided. Important advances in the field of sperm freezing began with the discovery of the cryoprotective effect of glycerol. The cryopreservation method, for future use, refers to stopping the biological activities of cells and tissues by freezing them below zero degrees. The main purpose of this process is the long-term storage of living cells or tissue at very low temperatures with minimal damage and loss of function. After the accidental discovery that glycerol can protect sperm against the harmful effects of freezing, the first scientific and modern sense of sperm freezing was performed in 1949 by Polge et al. After the sperm cell is stabilized with cryoprotectants in the freezing process, the cryoprotectants should be removed in the cooling, storage and thawing process in liquid nitrogen and finally the continuation of vitality should be ensured. The chemicals used in cryopreservation and the freezing-thawing process affect the viability of the cell. Cryoprotectants used during the freezing process protect the cell from freezing damage and have high hydrogen bonding properties. Cryoprotectants act by increasing the unfrozen fraction and reducing the amount of ions in the medium. The freezing speed during freezing processes should be well adjusted. While more ice crystals are formed in slow cooling, ice crystals are smaller in fast cooling. In this review, cryoprotectant substances used in cryopreservation, some cryopreservation techniques and the effects of cryopreservation on spermatozoa are mentioned.