Cryopreservation technique: comparison of Test yolk buffer versus SpermCryo and vapour versus computerised freezing.

Semen cryopreservation offers the possibility to maintain fertility over a long time period e.g. for male cancer patients. Although its use expands worldwide, there is no established method that can be referred to as an entrenched standard for routine laboratory use. Cryodamage is still a general phenomenon and the success of cryopreservation is affected on one side by the cryoprotective agent and on the other side by the technique of freezing. In this methodological study, we compared the newly offered SpermCryo (SC) with the standard used cryoprotectant Test yolk buffer (TYB). We could show that TYB is superior to SC. In addition, we compared the two mainly used techniques for cryopreservation: computerised slow-stage freezing versus nitrogen vapour fast freezing. Regarding the sperm post-thaw motility and viability, no significant difference was found between these two methods. In conclusion, TYB can be recommended as a cryomedium of first choice and the appropriate freezing technique can be selected according to the local facilities of the institution.