Comparison of motility characteristics and normal sperm morphology of human semen samples separated by percoll density gradient centrifugation.

The aim of this study was twofold: to investigate the ability of Percoll gradient centrifugation (52, 68, 84%) to fractionate semen samples according to motility quality and percentage normal morphology and to determine whether there is an association between sperm motility quality and percentage normal morphology. Sperm motility was evaluated using a Hamilton Thorn analyzer and normal sperm morphology was manually assessed according to the strict criteria (< or = 4, 5-14, and >14%). The majority of motility parameters and the percentage normal morphology were found to be significantly improved in the 84% Percoll fraction. The greatest effect was on the < or = 4% group, shifting the mean normal morphology percentage from 2.6 to 5.2%. Curvilinear velocity (VCL) and average path velocity (VAP) were the only two motility parameters that were significantly associated with the percentage normal morphology. Using a combined VCL, VAP vector the >14% group was found to have a significantly different value as compared to the 5-14 and < or = 4% groups. Percoll (discontinuous) gradient centrifugation can therefore play a significant role in the improvement of semen samples for use in assisted reproduction procedures. The VCL, VAP vector identified may also serve as an additional tool in the prediction of the fertility potential of sperm samples.