Movement characteristics of human spermatozoa collected from different layers of a discontinuous Percoll gradient

In order to evaluate the functional state of human spermatozoa separated on discontinuous Percoll gradient, sperm provided by 15 healthy volunteers were recovered from different layers (60, 70, 80, 90, 100%) of the gradient, then submitted to a complete analysis of sperm movement characteristics. This one was performed using a computer assisted system (Cellsoft, Cryo Resources, Ltd., NY, USA). In all fractions sperm motility was highly maintained during 24 h and all movement characteristics, with the exception of ALH, were different from that observed in seminal plasma. Curvilinear velocity (VCL), linearity (LIN), and percentage of hyper-activated sperm (HA) increased in relation to the Percoll concentration. Nevertheless there was no dramatic difference, concerning motion parameters, between 100%, 90%, and 80% Percoll fractions, which can thereby be pooled in case of insufficient sperm recovering in 100% fraction. On the contrary there is some doubt about the fertilizing ability of spermatozoa recovered in 70% and 60% Percoll layers, since VCL, LIN, and especially HA are severely decreased.