ABSTRACT
<p><b>Objective</b>To search for an effective method for cryopreservation of rare human sperm (RHS) by comparing the effect of RHS cryopreservation technology with that of conventional cryopreservation technology on post-thaw sperm from patients with severe oligozoospermia.</p><p><b>METHODS</b>Semen samples obtained from 82 patients with severe oligozoospermia were preserved by RHS cryopreservation technology, and another 24 samples cryopreserved by conventional technology, the former divided into groups A (sperm concentration < 1×10⁶/ml, n = 54) and B (1×10⁶/ml ≤ sperm concentration < 5×10⁶/ml, n = 28), and the latter included in group C (sperm concentration < 15×106 /ml, n = 24). The survival rate of post-thaw sperm and recovery rate of progressively motile sperm (PMS) were compared among the three groups.</p><p><b>RESULTS</b>The survival rate of post-thaw sperm was significantly higher in groups A and B than in C (［62.8 ± 18.7］% and ［61.9 ± 17.2］% vs ［50.7 ± 13.5］%, P < 0.05), and so was the recovery rate of PMS (［68.7 ± 18.4］% and ［70.7 ± 15.5］% vs ［29.2 ± 12.4］% , P < 0.05), but there were no statistically significant differences between groups A and B in either of the two parameters (P > 0.05).</p><p><b>CONCLUSIONS</b>The cryopreservation technology for rare human sperm may yield relatively stable post-thaw results and deserves a wide clinical application in preserving male fertility.</p>