Examining a cross-section of delicate tissue – such as that of a developing brain – is often a painstaking process, one that requires scientists to slice the fragile material as thinly as possible so light can pass through under a microscope. Fitting those pieces back together into a whole piece is also difficult and typically yields imperfect results.
But thanks to a new technique known as CLARITY, Linda Rinaman and Huiyuan Zheng, faculty in the Department of Neuroscience, are able to produce three-dimensional images using thicker slices of the brain and a simplified preparation method developed by Zheng. The result is a remarkably clear image of the tissue using vivid, fluorescent colors to differentiate between components within the sample. Even better, the sample remains intact, so researchers can examine the same piece of tissue several times without having to fit slices back together.
Zheng and Rinaman first learned about the CLARITY technology during a keynote lecture given by its creator, Karl Deisseroth of Stanford University. Intrigued by the ability to look at such clear images while retaining the integrity of the sample, they convinced the Dietrich School of Arts and Sciences to purchase a microscope capable of imaging CLARITY-processed samples, and install it in the Microscopy and Imaging Suite. Only a handful of these microscopes are currently in use in the United States.
The suite’s director, Tom Harper, was pleased by the new instrument’s quality and the fact that its objective lens is interchangeable with another confocal and multi-photon microscope from the same manufacturer.
“I really thought it would be a good addition to this facility,” Harper says. “It’s very cutting-edge. I’m always anxious to keep things upgraded.”
The procedure for using CLARITY to prepare samples and them image them on the new microscope is somewhat complex and requires specialized training, but Zheng was able to create a cheaper, simpler sample preparation method that is featured in the journal Brain Structure & Function and was presented at the Society for Neuroscience. In addition to overseeing the microscopy suite, Harper also created posters for the presentation using a 42-inch, six-color printer that captured the caliber of CLARITY’s images.
“He’s very patient. He’s a really good teacher,” says Rinaman, whom Harper trained in the use of the confocal microscope she and Zheng used to image the CLARITY samples.
Harper says visiting colleagues have been impressed when he shows them the suite’s latest instrument.
“We want to be able to have a modern facility that can perform the latest techniques, which are constantly being improved and developed,” he says.