[Study on cryosurvival rate of spermatozoa]

Semen samples obtained from 18 healthy volunteers and 42 subfertile men were divided into four groups: normospermia (n = 18), oligozoospermia (n = 21), asthenozoospermia (n = 10), and oligoasthenozoospermia (n = 11). After semen analysis, 10% glycerol was used as a cryoprotectant and the samples were stored in a liquid nitrogen tank at -196 degrees C. We studied the cryosurvival rate of thawed spermatozoa after cryopreservation at one week and one month. Further comparisons of the cryosurvival rate of spermatozoa thawed at 30 minutes, 60 minutes and 120 minutes were also made. Our results showed that: (1) there was no significant difference in the cryosurvival rate between spermatozoa preserved for one week and those preserved for one month (73.3% vs 68.7%, p greater than 0.05); (2) there was, however, a significant difference in the cryosurvival rate of spermatozoa thawed at 60 minutes and those thawed at 120 minutes (74.3% vs 60.2%, p less than 0.05); and (3) there was a significant difference in the cryosurvival rate of oligozoospermia/normospermia (39.0%) vs 73.3%, p less than 0.05) and oligoasthenozoospermia/normospermia (35.0% vs 73.3%, p less than 0.05). Thus, we suggest that artificial insemination with frozen semen be performed within one hour after thawing and that fresh semen is preferred to frozen semen in oligozoospermia and oligoasthenozoospermia patients undergoing artificial insemination.