OBJECTIVETo appraise the effect of single- and two-layer Percoll density gradient centrifugation in sperm separation.

METHODSTwenty semen specimens underwent single-(50%) and two-layer (90% and 45%) density gradient centrifugation, respectively. The sperm class analyzer (SCA) was used to analyze sperm density, motility and dynamic parameters and round cell density before and after the treatment.

RESULTSAfter separation, the sperm recovery rate of the single-layer method was (65.5 +/- 12.8)%, significantly higher than that of the two-layer method (P < 0.01). The percentages of grade a sperm of the single- and two-layer method were significantly higher than pre-treatment (P < 0.05, P < 0.01), that of the single-layer was significantly lower than that of the two-layer method (P < 0.05), but the percentage of grade c sperm of the former was significantly higher than that of the latter (P < 0.05). Compared with pre-treatment, the percentage of grade a + b sperm of the two-layer method was significantly higher (P < 0.05), while that of the single-layer method showed no significant difference (P > 0.05), and the round cell density of both the methods was significantly lower (P < 0.05, P < 0.01), with no significant differences between the two methods (P > 0.05).

CONCLUSIONThe single-layer method yields a higher rate of sperm recovery and causes little change in the sperm motility, while the two-layer method effects a lower rate and significantly improves sperm motility. Both the methods can efficiently separate sperm from round cells, and each has its own advantages and its application value in in vitro treatment of sperm.