Sperm-freezing and donor insemination.

A comparison between freezing of human sperm using glycerol or glycerol egg-yolk citrate is presented. Freezing was performed with a gradual lowering of the temperature using alchol-liquid nitrogen or by immersion into liquid nitrogen. Great variations were observed within the same donor sperm sample when the sperm was frozen according to different techniques and marked post-thaw, motility variations were also found between spermatozoa from different donors. No statistically significant differences were found in the number of pregnancies obtained following inseminations with sperm frozen according to the two methods.