Neuropathology in depth: the role of confocal microscopy

This review surveys the rapidly increasing applications of confocal microscopy in neuropathology and related areas of experimental neurology. The ability of this new instrument to "optically section" thick samples has opened up to microscopic examination a wide range of previously difficult specimens. The basic operating principle, trading field of view for axial resolution, is illustrated with a simple schematic comparison of conventional and confocal microscopes. Images can be collected in several different modes, utilizing fluorescence, reflectance, or transmitted light. The majority of the applications in neuropathology to date have focused on immunocytochemical labeling with peroxidase or fluorescent markers. New methods of specimen preparation designed explicitly for the confocal microscope are just beginning to appear. The trend toward new techniques that fully exploit the superior performance of confocal microscopes is expected to accelerate, which will quickly establish the confocal microscope as a routine laboratory tool for the neuropathologist.