Work smart, not hard: How array tomography can help increase the ultrastructure data output

Abstract

Transmission electron microscopy has been essential for understanding cell biology for over six decades. Volume electron microscopy tools, such as serial block face and focused ion beam scanning electron microscopy acquisition, brought a new era to ultrastructure analysis. “Array Tomography” (AT) refers to sequential image acquisition of resin‐embedded sample sections on a large support (coverslip, glass slide, silicon wafers) for immunolabeling with multiple fluorescent labels, occasionally combined with ultrastructure observation. Subsequently, the term was applied to generating and imaging a series of sections to acquire a 3D representation of a structure using Scanning Electron Microscopy (SEM). Although this is a valuable application, the potential of AT is to facilitate many tasks that are difficult or even impossible to obtain by Transmission Electron Microscopy (TEM). Due to the straightforward nature and versatility of AT sample preparation and image acquisition, the technique can be applied practically to any biological sample for selected sections or volume electron microscopy analysis. Furthermore, in addition to the benefits described here, AT is compatible with morphological analysis, multiplex immunolabeling, immune‐gold labelling, and correlative light and electron microscopy workflow applicable for single cells, tissue, and small organisms. This versatility makes AT attractive not only for basic research but as a diagnostic tool with a simplified routine.This article is protected by copyright. All rights reserved

Correlative light and electron microscopy for human brain and other biological models

“…While we use our protocol mostly to correlate LM images with TEM images from serial sectioning, it can be also coupled to correlative volume EM approaches such as serial block face scanning electron microscopy (SBF-SEM) or focused ion beam scanning electron microscopy (FIB-SEM) 19 . This protocol can also be adapted to collect sections on supports for array tomography (AT) on a scanning electron microscope if the high resolution of TEM is not required [20][21][22] . It is also possible to use our pipeline to verify the presence of targets of interest at large scale before investing in cryo-EM.…”

“…In neuroscience, volume EM techniques are frequently employed alongside CLEM, leading to numerous volume CLEM protocols, generally based on SEM techniques. Array tomography (AT) is used to enhance labeling on sections 21,22 or to automatically generate large volumes of neuropils at EM resolution 34 .…”