Efficient pig ICSI using Percoll-selected spermatozoa; evidence for the essential role of phospholipase C-ζ in ICSI success

In pigs, the damaged sperm membrane leads to leakage of phospholipase C-ζ (PLCζ), which has been identified as a sperm factor, and a reduction of oocyte-activating ability. In this study, we investigated whether sperm selected by Percoll gradient centrifugation (Percoll) have sufficient PLCζ, and whether the efficiency of fertilization and blastocyst formation after intracytoplasmic sperm injection (ICSI) using Percoll-selected sperm can be improved. Percoll-selected sperm (Percoll group) or sperm without Percoll selection (Control group) were used. A proportion of the oocytes injected with control sperm were subjected to electrical stimulation at 1 h after ICSI (Cont + ES group). It was found that the Percoll group showed a large amount of PLCζ in comparison with the Control group. Furthermore, application of Percoll-selected sperm for ICSI increased the efficiency of fertilization and embryo development. Thus, these results indicate the Percoll-selected sperm have sufficient PLCζ and high oocyte-activating ability after ICSI in pigs.