“Digital Holographic Microscopy” technique: First ever 3D film of a living sperm developed
The track of a single sperm cell with a bent tail, in two dimensions (left) and three dimensions (right). Credit: Biomedical Optics Express.
Scientists have developed the first 3-D movie of living sperm that can help doctors to select most viable sperm to improve odds during In Vitro Fertilization (IVF).
The 3-D imaging technique also known as Digital Holographic Microscopy (DHM), gives 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.
About the first 3-D movie of living sperm
- Provides detailed 3D 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.
- Generates a progressive series of holograms, scientists can watch sperm move and look for structural anomalies that make them less viable.
- Helpful for doctors: To sort the good sperm cells from the less viable ones, using a tracking system, that takes 3-D movies of living sperm and to show the sperm’s movement and behavior in real time.
- First technique for collecting data on sperm cell motility – a key predictor of IVF success – in three dimensions and over time.
At present, sperm concentration and mobility in semen are assessed either by subjective visual evaluation or a process known as Computer-Assisted Sperm Analysis (CASA).
How the researchers developed the First ever 3D film of a living sperm?
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.
- 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.
In other words, researchers 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 also their depth (z position) as well.
Note: In vitro fertilization (IVF) is a process by which an egg is fertilized by sperm outside the body. It is a major treatment for infertility when other methods of assisted reproductive technology have failed.