Cryopreservation of round-headed human sperm

AIM: To investigate the cryopreservation of round-headed (globozoospermia) human sperm. METHODS: Round-headed sperm samples (n=13) were obtained from 6 infertile men. Yolk-free cryoprotective medium and the two-step freezing were used in cryopreserving samples. Frozen sperm functions were examined by using motility evaluation, sperm head-tail membrane integrity test, and survival time test. RESULTS:The results showed that sperm motility, membrane integrity rates, survival time in vitro significantly lowered after thawing (n=13, P＜0.01). No acrosomal proteinase activity was detected in both fresh and frozen sperm groups (n=5). There were no significant difference in post-thawing motility between yolk-free cryoprotective medium and yolk medium, and between two-step freezing and multiple-step freezing (n=7, P＞0.05). CONCLUSION: Human round-headed sperm could undergo the freezing-thawing process. However, cryo-survival rates were low. Frozen sperm functions were significantly decreased. Yolk-free cryoprotective medium and two-step freezing could be used in the cryopreservation of round-headed sperm.