Received April 28, 1998
Accepted May 17, 1998

Introduction:The aim o f this study was to evaluate the characteristics of sperm motility in normozoospermic men, before and after cryopreservation using the liquid nitrogen vapor technique. Materiais and Methods:Semen samples were obtained from 15 healthy individuais with proven fertility. After abstinence of 48 hours, the ejaculates were collected by masturbation into sterile specimen cups. Slow-rate freezing using the liquid nitrogen vapor technique and TEST yolk-buffer with glycerol(1:1;v/v) as a cryoprotective agent were the major components of the cryopreservation technique. Sperm samples were analyzed on a computer-assisted motion analyzer before freezing and after thawing.Samples were analysed for percent motility, straight-line velocity(VSL), cuvilinear velocity(VCL), average path velocity(VAP), linearity(LIN) and amplitude of lateral head displacement (ALH).Sperm viability was assessed by eosin-nigrosin staining before freezing and after thawing. ResuIts:All seminal parameters were within normal range before freezing. Percent motility and viability showed significant decrease, 66% and 58%, respectively(P<0.0001) after thawing. Similarly, VSL, VCL, VAP and LlN significantly decreased(P<0.02) after cryopreservation. However, the percent change in ALH was statically significant(P=0.08). In spite of the decrease of ali motion parameters, the mean value still remained within normal range after thawing, except for VAP. Conclusion:Motility and viability are significantly impaired after cryopreservation of semen using the liquid nitrogen vapor technique in normozoospermic men. However, spermatozoa that survive the freeze-thawing process retain the majority of their motion characteristics within normal ranges, as evaluated by computer-assisted semen analysis. Computerized sperm analysis is an important tool to evaluate kinematics of cryothawed spermatozoa, since it yields more specific information than routine sperm analysis.