First 3-D movies of living sperm

February 11, 2014

WASHINGTON, Feb. 11, 2014--To improve their chances of success, in vitro fertilization (IVF) clinics need to assess the viability of the sperm they use. Now doctors may soon have a new technique to help them sort the good sperm cells from the less viable ones: a tracking system, developed by a team of researchers from four European institutions, that takes 3-D movies of living sperm. In addition to showing the sperm's movement and behavior in real time, the novel method simultaneously provides detailed 3-D imaging of the sperm's form and structure to detect potential infertility-causing anomalies, such as the "bent tail" that prevents the cells from swimming straight.

The researchers say this is the first technique for collecting data on sperm cell motility--a key predictor of IVF success--in three dimensions and over time. They describe their method in a paper published today in The Optical Society's (OSA) open-access journal Biomedical Optics Express.

Currently, sperm concentration and mobility in semen are assessed either by subjective visual evaluation or a process known as computer-assisted sperm analysis (CASA). While the latter provides more detail and fewer errors than the former, CASA still only allows tracking and imaging in two dimensions. In their new technique, the team of researchers from Italy and Belgium combined microscopy and holography--the creation of 3-D images--to visualize live sperm in not only two dimensions (the x and y positions) but according to their depth (z position) as well.

And, "by acquiring a video of the moving sperm in 3-D, we add a fourth dimension - time," said lead author Giuseppe Di Caprio of the Institute for Microelectronics and Microsystems 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.

"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 fertility--does 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 vacuoles--enclosed compartments filled with water plus organic and inorganic molecules--that 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 tracking system is to use the information gathered to develop a microchip-scale method for sorting good sperm cells from ones that are less viable.
-end-
The other institutions involved in this research are the National Institute of Optics of the NRC and the Center for Assisted Fertilization, both in Naples, and the Free University of Brussels in Belgium.

Paper: "4D tracking of clinical seminal samples for quantitative characterization of motility parameters," Di Caprio, G. et al., Biomedical Optics Express, Vol. 5, Issue 3, pp. 690-700 (2014).

EDITOR'S NOTE:
Images and a video file showing a single sperm cell being tracked are available to members of the media upon request. Contact Angela Stark, astark@osa.org.

About Biomedical Optics Express

Biomedical Optics Express is OSA's principal outlet for serving the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in the life sciences. The journal scope encompasses theoretical modeling and simulations, technology development, and biomedical studies and clinical applications. It is published by The Optical Society and edited by Joseph A. Izatt of Duke University. Biomedical Optics Express is an open-access journal and is available at no cost to readers online at http://www.OpticsInfoBase.org/BOE.

About OSA

Founded in 1916, The Optical Society (OSA) is the leading professional society for scientists, engineers, students and business leaders who fuel discoveries, shape real-world applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership programs, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of professionals in optics and photonics. For more information, visit http://www.osa.org.

The Optical Society

Related Sperm Articles from Brightsurf:

Nut consumption causes changes in sperm DNA function
Researchers have evaluated for the first time the effect of a short/middle-term consumption of a mixture of tree nuts (almonds, hazelnuts and walnuts) on sperm DNA methylation patterns in healthy individuals reporting eating a Western-style diet.

Collecting sperm from Covid-19 patients
How does Covid-19 affect sperm and thus the next generation┬┤s immune system?

Paleontology -- The oldest known sperm cells
An international team of paleontologists has discovered giant sperm cells in a 100-million year-old female ostracod preserved in a sample of amber.

Research captures how human sperm swim in 3D
Using state-of-the-art 3D microscopy and mathematics, Dr Hermes Gadêlha from the University of Bristol, Dr Gabriel Corkidi and Dr Alberto Darszon from the Universidad Nacional Autonoma de Mexico, have reconstructed the movement of the sperm tail in 3D with high-precision.

Overweight and obesity are associated with a low sperm quality
Researchers from the Rovira i Virgili University in collaboration with researchers from the University of Utah have carried out a systematic review and meta-analysis evaluating the association between adiposity (normal weight, overweight, obesity, and low weight) and the sperm quality.

Diet has rapid effects on sperm quality
Sperm are influenced by diet, and the effects arise rapidly.

Sperm may offer the uterus a 'secret handshake'
Why does it take 200 million sperm to fertilize a single egg?

Long duration of sperm freezing makes no difference to live birth rates in large sperm bank study
Despite a time limit imposed in many countries on the freeze-storage of sperm, a new study from China has found that the long-term cryopreservation of semen in a sperm bank does not affect future clinical outcomes.

An important function of non-nucleated sperm
Some animals form characteristic infertile spermatozoa called parasperm, which differ in size and shape compared to fertile sperm produced by single males.

DNA of sperm taken from testicles of infertile men 'as good as sperm from fertile men'
Scientists have found that sperm DNA from the testicles of many infertile men is as good as that of ejaculated sperm of fertile men.

Read More: Sperm News and Sperm Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.