Comparative analysis of motility characteristics of Percoll-selected spermatozoa populations from fresh and cryopreserved semen

The proportion and quality of motility of spermatozoa in normozoospermicejaculates were assessed using computerassisted semen analysis.The ejaculate was split and the motility re-assessed followingseparation on a Percoll gradient with or without cryomediumand cryopreservation. Cryopreservation caused a significantdecrease in the proportion of motile spermatozoa and in theirvelocity and amplitude of lateral head displacement. The initialdecrease in the proportion of motile spermatozoa was found tobe in part an effect of the cryomedium. The use of Percoll gradientseparation did not initially change these effects but after4 h incubation differences in velocity and amplitude of lateralhead displacement between samples were no longer evident. Percoll-selected,cryopreserved spermatozoa had both a stable proportion of motilespermatozoa and a stable velocity for at least 48 h, whereasin fresh spermatozoa populations, similarly separated usingPercoll, the proportion of motile spermatozoa had decreasedby 24 h and the velocity was lower at 48 h. Percoll preparationis an effective method for the selection of motile spermatozoafrom cryopreserved semen which, after a short incubation, havesimilar motility characteristics to fresh spermatozoa.