Funnel procedure to separate human sperm with good motility.

Penetration of human sperm into a underlaying Percoll layer is very effective in isolating forward motile sperm. A plastic funnel, the bottom of which having been plugged with a 1.0-ml disposable syringe, was used as a separation vessel. Ejaculated semen (2.0 ml) was loaded on 2.0 ml of 80% Percoll; after allowing to stand 60 min, forward motile sperm penetrating into the lower part of Percoll layer (1.0 ml) were collected into the syringe. Sperm motility was enhanced to 91.5% +/- 3.3% regardless of the original motility (48.4% +/- 14.6%) with a mean recovery of 34.1% +/- 6.8% (n = 22). Measurement of residual lactate dehydrogenase activity suggested that seminal plasma was excluded almost completely from the purified sperm fraction.