Effect of sperm storage and selection techniques on sperm parameters.

Sperm cryopreservation preserves the fertility of cancer patients undergoing chemotherapy, ensures sperm are available at the time of oocyte retrieval in assisted reproductive technology (ART) procedures and avoids the need for repeated sperm extraction surgeries in azoospermic patients. Conventional methods of cryopreservation involve storage in liquid nitrogen (LN2), which causes a significant decline in sperm parameters such as motility and viability and results in DNA damage. Newer methods of sperm cryopreservation such as the LN2 vapor method, vitrification, and experimental methods such as lyophilization, have significant advantages over the conventional methods in terms of cost effectiveness and ease of use. Density gradient centrifugation (DGC), swim up, and magnetic assisted cell sorting (MACS) can be used prior to or post-cryopreservation to improve post-thaw sperm quality. Cryopreservation in special carriers such as cryoloops and empty zona prevents the loss of small numbers of sperm during cryopreservation. This article will discuss these sperm preservation and selection techniques.