Ice age: Cryopreservation in assisted reproduction – An update

Yardimci Üreme Tekni̇kleri̇ Ve Ferti̇li̇te Prezervasyonunda Kri̇yoprezervason

“…Single embryo transfer and cryopreservation of surplus embryos is also an effective policy that diminishes the multiple pregnancy rates and enhances the cumulative pregnancy rates (2,4). Cryopreservation has facilitated the introduction of elective deferred embryo transfers in cases which necessitate pre-implantation genetic diagnosis or screening (5). By cooling Mechanical damage by ice crystal formation, osmotic stress, membrane permeability and cytoskeletal structural changes due to the cold shock are the major problems that may cause damage to the cells (4,6).…”

“…Since its introduction and first reported success, human sperm cryopreservation has been regarded as a useful procedure for treatment of male infertility. The small structure and relative abundance create an advantage when compared to oocyte or embryos in development of effective freezing protocols, as smaller structures are proved to be less susceptible to damage by ice-crystal formation during the cryopreservation (5,14).…”

“…Traditionally, slow-freezing and vitrification protocols were considered comparably acceptable in the clinical setting (5). Slow-freezing protocols were the first method used to successfully freeze spermatozoa and remain the most commonly used technique worldwide.…”

“…Freezing procedure induces a reduction in membrane fluidity which results in low sperm survival and motility (14). But the high numbers of spermatozoa obtained per sample made this lower survival rates acceptable (5). Pre-freezing semen quality parameters, such as sperm motility and the abstinence period of sperm donors, can also affect the cryosurvival rates of post-thaw spermatozoa (14).…”

“…However, it requires a very high concentrations of P-CPAs when compared with slow freezing, which represents the main limitation of the procedure due to cytotoxic effects of the cryoprotectants (4). But more recent refinements in vitrification protocols specific to spermatozoa have eliminated the need for cryoprotectants and improved the post-thaw vitality, motility and DNA fragmentation (5).…”