Advances in Microscopy Techniques

Context.-Advances in microscopy enable visualization of a broad range of new morphologic features. Objective.-To review and illustrate advances in microscopy with relevance to pathologists. Data Sources.-Literature review and new observations. Results.-Fluorescence microscopy enables multiantigen detection; allows novel optical-sectioning techniques, with some advantages compared to paraffin sectioning; and permits live-cell imaging. Live-cell imaging allows pathologists to move from a period when all diagnostic expertise was reliant on interpreting static images to a period when cellular dynamics can play a role in diagnosis. New techniques have bypassed by about 100-fold what had long been believed to be a limit to the resolution of light microscopy. Fluorescence resonance energy transfer (FRET) appears capable of visualizing diagnostically relevant molecular events in living or fixed cells that are immeasurable by other molecular techniques. We describe applications of 2-photon microscopy, FRET, structured illumination, and the subdiffraction techniques of near-field microscopy, photoactivated localization microscopy, stochastic optical reconstruction microscopy, and stimulated emission depletion microscopy. Conclusion.-New microscopy techniques present opportunities for pathologists to develop improved diagnostic tests. (Arch Pathol Lab Med. 2011;135:255-263)