BIOIMAGING/CELL BIOLOGY/MICROSCOPY: Refraction alteration and advanced microscopy enable 3-D view of single cells in intact tissue

A new microscopy method developed by an international research group is allowing 3-D observation of single nerve cells in intact tissue.

A new microscopy method developed by an international research group is allowing 3-D observation of single nerve cells in intact tissue.1 The approach was designed to facilitate understanding of whether axons severed in a spinal cord injury can be stimulated to regenerate-and it could be useful in other biomedical applications, including cancer research. Previously, researchers were able to observe axon growth only by cutting tissue into ultra-thin slices for microscopic study—an approach that is fraught with difficulty (2-D sections provide an inaccurate representation of spatial distribution and progression, and producing virtual 3-D models on this basis is painstaking and highly fallible).

The new method is based on Hans Ulrich Dodt's (Technical University of Vienna, Austria) ultramicroscopy technique for fast 3-D fluorescence imaging of neuronal networks in the whole mouse brain. Researchers at the Max Planck Institute for Neurobiology (Martinsried, Germany) figured out a way to facilitate the work: They replaced the water in spinal cord tissue with an emulsion that matches the refraction of proteins in the tissue—thus rendering the tissue transparent. Then, using fluorescent dyes to stain individual nerve cells, the researchers were able to trace their paths from all angles.

The researchers say that the method could also be used to depict the blood capillary system or visualize the way a tumor is embedded in tissue.

1. A. Erturk et al., Nat. Med., doi:10. 1038/nm.2600 (2011).

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