Fractions of Percoll eliminated sperm: Increased sperm yield in Percoll wash

Sperm preparation by Percoll is one of the most widely used techniques, but it has the disadvantage of producing a low final yield of motile sperm. This study compared the quality of Percoll-eliminated sperm with that of Percoll recovered sperm to determine if the profile of the Percoll preparation could be improved. Semen specimens were fractionated by discontinuous Percoll gradient column. This resulted in 4 sperm fractions: sperm retained in the semen (SRS), sperm clumped at the interface of 40 and 80% Percoll (SCI), sperm scattered in the column (SSC), and sperm-forming pellet, called Percoll-recovered sperm (PRS). The sperm fractions were evaluated for count, motility, viability, vitality, and morphology. The SRS exhibited the lowest motility, viability, and vitality (40, 68, and 64%, respectively), which were significantly different from those of SCI, SSC, and PRS. The motility, viability, and vitality differences between SSC and PRS did not reach a statistically significant level. Good motility (grades a and b) was found in SSC (73%) when compared with that of PRS (82%). The lower part of SSC and PRS exhibited identical sperm morphology. The Percoll sperm recovery was 18%, but if SSC is combined with PRS, the total recovery becomes 40%. These data suggest that the SSC fraction, particularly the lower part, which maintains the physical contact with the PRS, can be pooled together to increase the final sperm yield without compromising the quality of the sperm to be used for insemination.