Ultrastructural parameters of fertile cryopreserved human sperm.

Two hundred and forty-four cryopreserved semen samples were used for artificial insemination by donor (AID). All samples were examined for motility and concentration. Thirty of the samples resulted in pregnancies. These samples were further examined ultrastructurally. There was no difference in sperm motility or concentration between the samples that did or did not result in a pregnancy. The ultrastructural characteristics of the samples that resulted in pregnancies revealed that only 15% of sperm (SD = 7.67) possessed normal morphology and had undamaged acrosomes after cryopreservation.