Motility characteristics of human sperm, nonfrozen and cryopreserved

Ejaculates (1651) obtained by masturbation from 88 donors were evaluated for count, motility, and kinetics. After the initial evaluation the ejaculates were frozen in liquid nitrogen, thawed 24 hr later, and assessed for postthaw motility and kinetics. The ejaculates were then divided into seventeen groups according to sperm count and evaluated to determine if direct relationships exist between prefreeze and thawed semen characteristics. The average sperm count was 151 X 10(6) sperm/ml. The freezing process resulted in a reduction of motility from a mean of 85% to a mean of 52%. Postthaw motility increased with sperm count up to 120 X 10(6) sperm/ml where there appeared to be no further effect. Linear regression analysis demonstrated a high correlation between prefreeze motility and postthaw motility (r = 0.947). Cryopreservtion of human spermatozoa results in a significant reduction of motility. A direct relationship exists between prefreeze and postthaw motility and prefreeze motility may be an important factor in evaluating the potential of an ejactulate to withstand cryopreservation.