En bloc optical sectioning of resin-embedded specimens using a confocal laser scanning microscope

Reconstruction of 3D structures of specimens embedded for light or electron microscopy is usually achieved by cutting serial sections through the tiss ues, then assembling the images from each section to reconstruct the origin al structure or feature. This is both time-consuming and destructive, and m ay lead to areas of particular interest being missed, This paper describes a method of examining specimens which have been fixed in glutaraldehyde and embedded in epoxy resin, by utilising the autofluorescence preserved or en hanced by aldehyde fixation, and by using a confocal laser scanning microsc ope to section optically such specimens in the block down to a depth of abo ut 200 mu m. In this way, the accurate estimation of the depth of particula r features could be used to facilitate subsequent sectioning at the light m icroscope or electron microscope level for more detailed studies, and 3D im ages of tissues/structures within the block could be easily prepared if req uired.