Have you ever seen a cell? If you have, then it was probably a two-dimensional (2D) image in a text book, where else; or if you were fortunate enough, you had the chance of seeing a microscopic image on a slide. The same goes for scientists. Its hard enough to envision something way smaller than you’d imagine, than to zoom in on it and capture a three-dimensional (3D) image. Fortunately enough, scientists have made an imaging breakthrough technology that led them to capture 3D footage of cells moving through the body — and its totally way awesome than you could have ever imagined.
Related media: Immune Cell Migration In The Zebrafish Inner Ear
Let’s Get Ready To Wriggle
The video above depicts the inner ear of a zebrafish — you know, that little 4 centimeter (an inch and a half). The objects in this footage are very, very small. Here, a fiery yellow immune cell rolls on through gobbling up bright-blue particles of sugar. The immune cell morphs and stretches as it wriggles through the organ, looking nothing like what our text books depicts. Where’s your 2D cell diagram now?
For centuries, scientists have had the ability to see living cells with aid of microscopes, but all that while, they had to capture the cells on isolated glass slides to hold the image steady from blurring. That’s not exactly their natural state: Cells are more likely to cluster in wriggling groups. Even with modern image resolution technology, its too slow to follow up their actions in 3D, or too bright to really show what the cells look like in their natural environments.
“That’s a problem,” says Eric Betzig, a physicist at the Howard Hughes Medical Institute’s Janelia Research Campus, and the team’s led researcher behind this breakthrough. “This raises the nagging doubt that we are not seeing cells in their native state, happily ensconced in the organism in which they evolved.”
The Breakthrough Imaging Technology
Another scientific field of study that deals with blurry images is astronomy. The churning atmosphere above our heads is what makes the stars appear to twinkle, which is a big deal of a problem to astronomers using ground-based telescopes. To resolve this issue, astronomers use a method known as adaptive optics. This requires the use of mirrors that computers can deform on purpose to correct these atmospheric distortions in real time.
They need to have a bright star as a reference point the computer can use to measure how blurring it is — but barring that, they can just shine a laser where a star would be and measure the blurring of that instead. That being the case, Betzig and his team took a page from their book and combined adaptive optics with a modern technology known as lattice light sheet microscopy.
This breakthrough imaging technology flashes an ultra-thin sheet of light through the cell, creating a high-resolution 3D film from the 2D images it captures in real time. The scientists focused one adaptive optical system at the side view to maintain the lattice light sheet’s illumination, and focused another adaptive system overhead. Later, they could shine their reference laser through either pathway to let the optics self-correct, achieving a super-sharp 3D image.
3D Image Microscopy, And The Future
We’ve had this technology at our fingertips, but it’s been too complicated and expensive to be practical, even for advanced research labs. Betzig wants to change that.
“Technical demonstrations and publications don’t amount to a hill of beans,” he says. “The only metric by which a microscope should be judged is how many people use it, and the significance of what they discover with it.”
While his current microscope fills a 10-foot-long table, his team is working on a smaller one they hope will fit on a small desk and sport a more reasonable price tag. In the true spirit of science, however, the team will make their plans freely available to other scientists who want to build their own microscopes.
“It’s a bit of a Frankenstein’s monster right now,” as Betzig concludes, “If you really want to understand the cell in vivo, and image it with the quality possible in vitro, this is the price of admission.”
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Written by: Nana Kwadwo, Sun, Feb 24, 2019.