Separation of human spermatozoa with hyaluronic acid induces, and Percoll inhibits, the acrosome reaction.

The effect on the acrosome reaction of human spermatozoa of two widely used sperm separation media, hyaluronic acid (Sperm Select) and Percoll, was studied. Viable and highly motile fractions of human spermatozoa were separated from seminal plasma using self-migration on a Percoll gradient. After translocation of separated spermatozoa from the Percoll solution to a culture medium, serum, Percoll or hyaluronic acid (Sperm Select) was added to aliquots of the spermatozoa containing culture medium. At increasing time intervals, the influx of 45Ca2+ into spermatozoa was measured and the concentration of viable spermatozoa that had undergone the acrosome reaction was analysed using the triple stain technique. Serum was found to be necessary to support sperm motility and viability. Compared to culture medium with serum only, addition of hyaluronic acid induced influx of 45Ca2+ and the acrosome reaction, whilst Percoll inhibited both of these actions. Hyaluronic acid (Sperm Select) added to spermatozoa separated by a 'swim-up' method induced, and the addition of Percoll inhibited, influx of 45Ca2+ when compared to the addition of culture medium with serum only. This study demonstrates that both hyaluronic acid (Sperm Select) and Percoll affect the acrosome reaction and the prerequisite for Ca2+ influx in human spermatozoa. These effects should be taken into consideration when using these media for preparation of spermatozoa for insemination or for fertilization in vitro.