Scientists say watching a sperm specimen move and behave in real time will allow them to better evaluate the viability of reproductive cells for in vitro fertilization. Effectively observing sperm morphology (size and shape) and motility (ability to swim toward an egg) are the keys to increasing the likelihood of insemination.
Previously, scientists have only been able to observe a sperm's performance in two dimensions, charting the sperm's movement in relation to the x and y axes. But new laser technology has allowed scientists to add a third dimension.
And, "by acquiring a video of the moving sperm in 3-D, we add a fourth dimension -- time," explained Giuseppe Di Caprio, lead author of the study, which involved several research institutions, including the Institute for Microelectronics and Microsystems of the National Research Council in Naples, Italy, and Harvard University in Cambridge, Mass.
By trapping a living sperm between two lasers, scientists are able to -- with the help of a microscope -- generate real-time video of the sperm's movement based on how the specimen interfered with the laser beams.
"Viewing a progressive series of these holograms in a real-time video, we can observe how the sperm move and determine if that movement is affected by any abnormalities in their shape and structure," Di Caprio said.
Scientists have been able to observe morphology and motility data before, but real-time video allows them to see how one effects the other and offers a more accurate image of how sperm will perform when it really counts. For example, scientists were able to witness how small abnormalities -- such as a bent tail -- affect the way a sperm specimen swims.
Di Caprio says the new breakthrough gets fertility scientists closer to being able to quickly and efficiently separate the good sperm from the bad.
The details of the study were published in the latest issue of the Optical Society's (OSA) open-access journal Biomedical Optics Express.
[Biomedical Optics Express]