Survival of Spermatozoa in a Human Sperm Bank

Human semen was frozen and stored in liquid nitrogen for periods of time up to eight years and two months. A total of 1,764 vials containing 1.1 ml of semen from 533 ejaculates provided by 207 donors were frozen. The freezing and thawing process induced a loss of approximately 50% of the original motility. Storage in liquid nitrogen for periods up to 36 months resulted in no further significant loss in mean motility. However, after this time, a progressive significant loss in motility was observed throughout the period of this study. Specimens with initial sperm counts between 40 and 200 million/ml and initial motilities between 60% and 89% appeared to withstand long-term storage best.