A multinational, multidisciplinary team of European researchers has devised a three-dimensional (3-D) video tracking system that allows the observer to watch living sperm in motion. The behaviors of sperm in motion — motility — are a marker of health and are essential factors determining in vitro fertilization (IVF) success. With the perfection of the technology, its developers expect it to become a powerful tool fertility specialist can use to assess sperm viability.
“By acquiring a video of the moving sperm in 3-D, we add a fourth dimension — time,” says Giuseppe Di Caprio, lead author of the recently published report of the new tracking system. The researchers used a technology known as digital holographic microscopy (DHM) to create a holographic image that allows for visual assessment of the sperm and monitors its movements in real time, another indicator of health.
Today’s sperm assessments include subjective visual evaluation or computer-assisted sperm analysis (CASA). The CASA method is more detailed and more accurate than the visual check but is limited to assessment in two dimensions — x and y, or top to bottom and left to right. By adding the third dimension of depth (z), a more accurate assessment can be made.
The research team used both existing methods to obtain a preliminary assessment of sperm health and tested that assessment against DHM assessment. Di Caprio describes an “unprecedented bonus of seeing cause and effect relationships” between sperm morphology (shape) and motility (movement).
“For example,” Di Caprio said, “we found that most of the sperm cells we observed swim along in one plane as expected. However, with the more detailed analysis provided by DHM, we also were able to show that this ‘in-plane’ movement — which we believe is linked to higher potential for fertility — does not occur when there are morphological anomalies such as sperm with misshapen heads or ‘bent tails.’”
Future experiments are expected, one of which will focus on sperm cell vacuoles. Vacuoles are enclosed sacs on the surface of the sperm cell that is filled with water and organic and inorganic molecules. It is currently unknown how or if the vacuoles affect the sperm cell’s fertility.
Di Caprio is affiliated with the National Research Council’s (NRC’s) Institute for Microelectronics and Microsystems in Naples, Italy, and Harvard University in Cambridge, Massachusetts. Joining forces with Di Caprio are scientists from the CRC’s National Institute of Optics and the Center for Assisted Fertilization, both headquartered in Naples, and from the Free University of Brussels, Belgium.
Source: Stark, Angela. “First 3-D Movies of Living Sperm.” OSA. The Optical Society. Feb 11, 2014. Web. Feb 22, 2014.