Soon, 3D technique to sort fast sperms from slow ones

Here comes a tracking system that makes 3D movies of living sperm to detect potential infertility-causing anomalies - such as the 'bent tail' that prevents the cells from swimming straight.

This is the first technique for collecting data on sperm cell motility - a key predictor of in vitro fertilisation (IVF) success - in three dimensions and over time, said researchers.

Currently, sperm concentration and mobility in semen are assessed either by subjective visual evaluation or a process known as computer-assisted sperm analysis (CASA).

In their new technique, the team of researchers from Italy and Belgium combined microscopy and holography - the creation of 3D images - to visualise live sperm in not only two dimensions but according to their depth as well.

"By acquiring a video of the moving sperm in 3D, we add a fourth dimension - time," explained lead author Giuseppe Di Caprio of the National Research Council (NRC) in Naples, Italy, and Harvard University in Cambridge, Mass.

To achieve their new tracking system, the researchers first separated laser light into two beams.

They transmitted one beam through a dish containing live, swimming sperm cells and then recombined it, after magnification through a microscope with the second beam.

"Viewing a progressive series of these images 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," informed Di Caprio.

To improve their chances of success, IVF clinics need to assess the viability of the sperm they use.

Now the international research team would attempt to exploit the new technique to define best-quality sperm for IVF.

The other institutions involved in this research are the National Institute of Optics of the NRC and the Center for Assisted Fertilisation, both in Naples, and the Free University of Brussels in Belgium, said the study published in the journal Biomedical Optics Express.