Laser light-scattering study of the effect of washing on sperm motility

The effect of washing on human sperm motility was measured by means of dynamic laser light-scattering spectroscopy. Semen samples from 24 fertile donors were diluted with Biggers, Whitten and Whittingham (BWW) medium and subsequently centrifuged at one of the following forces: 235 × g, 325 × g, 400 x g, 470 × g, 500 × g, 600 × g, and 800 × g. The duration of centrifugation was 8 minutes for the first wash, 6 minutes for the second wash, and 3 minutes for the third wash. Sperm motility was evaluated in terms of the root mean square swimming speed of the spermatozoa and the mean migration rate of washed spermatozoa in estrous bovine cervical mucus (BCM). It was found that sperm motility and viability were improved when semen samples were washed at 235 × g, even after three washes. However, washing at forces of 600 × g or more reduced sperm motility and also their ability to penetrate cervical mucus in vitro. Repeated washing at forces between 300 × g and 500 × g had little deleterious effect on sperm motility.