The most common cryoprotectant in human sperm cryopreservation is glycerol, often combined with egg yolk or a synthetic protein alternative in a base extender. Cryoprotectant composition does not alter the storage temperature requirement; all frozen sperm must be maintained at minus 196 degrees Celsius in liquid nitrogen. What cryoprotectant choice does affect is post-thaw motility, DNA fragmentation rates, and compatibility with the downstream insemination or IVF procedure. The storage vessel remains a constant: a quality liquid nitrogen dewar for cell storage from a specialist supplier like Cryolab.