Sperm swimming in a high-velocity path with high lateral head deflection and low linearity may be “hyperactivated”. This occurs normally in the oviduct and as sperm bind to the zona pellucida surrounding the egg. It is believed that this motility pattern is partly necessary for sperm to penetrate the zona pellucida and reach the egg membrane. Thus, failure of sperm to hyperactivate during incubation in vitro for at least 3 hours is an indication that they may fail this essential step leading to fertilization. Another pattern, spiraling, is an indicator that sperm are “capacitated”, that is, preparing to fertilize the egg. Both motility patterns are expected once sperm are free of semen and cultured under specific conditions that mimic the oviduct.
We test spiraling and hyperactivation patterns under several conditions and in the presence of stimulators of motility, such as phosphodiesterase inhibitors. Analyses are performed by computerized sperm motility analysis in an IVOS anlalyzer.
Above: The digitized path of a hyperactivating sperm. The green path is the point-to-point path for 0.5 sec at 60 frames per second. The red line is the 5-point running average.
