In this protocol, we describe the specific steps required to prepare human postmortem brain samples for ultrastructural microglial analysis. A detailed procedure is provided to improve the ultrastructural quality of the samples, using aldehyde fixatives followed by immunoperoxidase staining of allograft inflammatory factor 1 (AIF1, also known as IBA1), a marker of myeloid cells, and cluster of differentiation 68 (CD68), a marker of phagolysosomal activity. Additionally, we describe an osmium-thiocarbohydrazide-osmium (OTO) post-fixation method that preserves and increases the contrast of cellular membranes in human postmortem brain samples, as well as the steps necessary to acquire scanning electron microscopy (SEM) images of microglial cell bodies. In the last section, we cover the quantitative analysis of various microglial cytoplasmic organelles and their interactions with other parenchymal elements.
Keywords: Human postmortem brain samples; Intercellular relationships; Microglia; Phagolysosomal activity; Scanning electron microscopy; Ultrastructural analysis.
© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.