"The superimposed beams generate an interference pattern that we can record on camera," Di Caprio explained. "The resulting image is a hologram containing information relative to the morphologies of the sperm and their positioning in three-dimensional space. 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 says that the 3-D imaging technique, known formally as digital holographic microscopy (DHM), yields morphology and motility data on sperm consistent with that found in previous studies, but with the unprecedented bonus of seeing cause and effect relationships between the two.
"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 fertilitydoes not occur when there are morphological anomalies such as sperm with misshapen heads or 'bent tails.'"
Now that the efficiency of sperm tracking via DHM has been demonstrated, Di Caprio says that the international research team will next attempt to exploit its capabilities for defining the best-quality sperm for IVF.
"In one future experiment, we want to study sperm cells with vacuolesenclosed compartments filled with water plus organic and inorganic moleculesthat rest on the cell surface," he said. Using DHM to assess the affected sperms' motility, the team can determine if having vacuoles results in reduced fertility.
Di Caprio says that the long-term goal of such experiments and others using the new track
|Contact: Angela Stark|
The Optical Society