Profiles of sperm morphology and motility after discontinuous multiple-step Percoll density gradient centrifugation

Morphology and motility are important parameters for assessing the fertilizing capacity of spermatozoa. This investigation reports a systematic study on the profiles of these parameters after Percoll gradient centrifugation. Spermatozoa from normal human semen were fractionated by discontinuous Percoll gradients (30%, 45%, 75%, 90%). Spermatozoa washed with Earle's balanced salt solution were used as a control. After centrifugation, sperm morphology was evaluated according to strict criteria; motility was assessed by a computer-assisted semen analysis system. The results showed that the percentage of spermatozoa with normal morphology increased, while those with severe morphological defects decreased, as the density of Percoll increased. The percentages of motile spermatozoa and hyperactivated spermatozoa, and the velocity and amplitude of lateral head displacement of the spermatozoa were significantly higher in the 75% and 90% Percoll fractions than that in the 30% and 45% ones, and in the control. These results demonstrated that Percoll density gradient centrifugation enriched spermatozoa in terms of morphology and motility.