A typical electron micrograph is a black-and-white [BLP1] image that provides detailed information on the ultrastructure of cells and tissues. Such images can be digitally colored using a computer to highlight particular cell components of interest, but those enhancements are based on the scientists’ interpretation. A new method uses rare earth metals to label specific molecules in cells, which are then visualized as a separate color overlay to the electron micrograph. In this example, the labeled molecules belong to two different astrocytes in a mouse brain; one appears green and the other red superimposed on the black and white image. The astrocytes’ processes can be seen making contact with the same synapse — a finding that would have likely been missed in a black and white image.
Polymers containing two different rare earth metals, such as lanthanum, cerium, or praseodymium, are specifically generated in adjacent astrocytes and visualized by electron energy-loss spectroscopy and energy-filtered transmission electron microscopy. The astrocyte processes are approximately 200 nanometers wide
Stephen R. Adams, PhD, Department of Pharmacology, and Ranjan Ramachandra, PhD, Department of Neuroscience, University of California San Diego, CA