First-year medical students at Washington University School of Medicine have much to learn about the structure of the body and its cells. Soon they will have new inspiration for that learning journey in the form of a series of detailed black-and-white electron micrographs of cells and their interiors created by John Heuser, MD, professor of cell biology and physiology.
The images will be placed on permanent display in the third floor of the Farrell Learning and Teaching Center (FLTC), near the histology laboratories where first-year students study the structures of cells and tissues.
To obtain detailed images of the contents of cells, Heuser pioneered a technique he calls “quick-freeze deep-etch” electron microscopy. The natural environment in cells is too watery and transparent for electron microscopes, so Heuser devised a way to freeze cells in about 1/10,000th of a second by exposing them to a piece of copper cooled to minus 450 degrees Fahrenheit. The cells can then be split open and coated with an ultrathin film of metallic platinum to enable imaging with an electron microscope.
Heuser compares the technique to using a stroboscopic flash to freeze the action in a photograph. He has used it to create images of cells and tissues that are not only scientifically insightful but also artistically intriguing. The collection of images being put on permanent display at the FLTC includes a picture produced using techniques that allow a viewer wearing 3-D glasses to see depth in the image.
The images have allowed Heuser and his colleagues to learn more about the uptake and secretion of materials into and out of cells, the mechanism of entry of dangerous viruses into cells and the rapid movements of cells ranging from contracting muscle cells to swimming sperm.
Heuser was elected to the National Academy of Sciences earlier this year for his groundbreaking discovery of the recycling of synaptic vesicles in nerve terminals. These are small compartments that secrete the chemicals that mediate the transmission of messages between nerves. This led to a general realization in cell biology that membrane recycling occurs in all cells, not just in nerves, and is an important component of all cells’ ability to take up materials from their environment and to secrete material outward.
“John really took electron microscopy to a new level to answer important questions about how synapses work,” Paul Bridgman, PhD, professor of anatomy and neurobiology, said at a reception honoring the addition of the micrographs to the FLTC.
Bridgman and Krikor Dikranian, MD, PhD, associate professor of anatomy and of physical therapy, arranged a temporary exhibition of the micrographs on the first floor of the FLTC earlier this year.