Syw. Chan et al., HUMAN SPERMATOZOAL TAIL HYPOOSMOTIC SWELLING TEST, MOTILITY CHARACTERISTICS IN HYPOTONIC SALINE, AND SURVIVAL OF SPERMATOZOA AFTER CRYOPRESERVATION, Human reproduction, 8(5), 1993, pp. 717-721
Normozoospermic semen samples (n = 82) were examined to investigate wh
ether the degree of sperm tail swelling in hypo-osmotic medium (fructo
se and sodium citrate; 150 mOsm/l), and motility characteristics after
a 15-min exposure to hypotonic saline (sodium chloride; 150 mOsm/l) c
ould predict the cryosurvival rate (% post-thaw motility/% pre-freeze
motility X 100%) of spermatozoa after cryopreservation by the liquid n
itrogen vapour freezing method using the TEST-glycerol-egg yolk buffer
. The CellSoft automated semen analyser was used to analyse sperm moti
lity in pre-freeze and post-thaw semen samples, and after exposure to
hypotonic saline. Sperm tail hypo-osmotic swelling and sperm motility
in pre-freeze semen showed no significant correlations (P > 0.05) with
the cryosurvival rate. There were significant correlations (P < 0.05)
between the cryosurvival rate and the following sperm motility parame
ters in hypotonic saline: % motility (r = 0.2846), motility index (% m
otility X curvilinear velocity; r = 0.2809) and % decrease in motility
index from the baseline value in semen (r = 0.3378). The % decrease i
n motility index after hypotonic saline treatment was significantly le
ss (P < 0.05) in the normal (greater-than-or-equal-to 50% cryosurvival
rate; mean +/- SEM 5.9 +/- 3.2%; n = 33) compared with the subnormal
(< 50% cryosurvival rate; 27.3 +/- 4.8%; n = 49) cryosurvival groups.
This parameter was also determined, by multivariate discriminant analy
sis, to be capable of classifying each pre-freeze semen sample into ei
ther cryosurvival group with 69.5% accuracy. These results indicate th
at cryosurvival of spermatozoa is not dependent on pre-freeze motility
characteristics, and that results of the tail hypo-osmotic swelling t
est cannot be utilized to predict the susceptibility of human spermato
zoa to cryoinjury. Studies on the motility characteristics in an artif
icial medium such as hypotonic saline, while unable to provide a power
ful predictive assay, may help to provide useful information about the
survival of human spermatozoa after cryopreservation.