Optimization of Brain Clearing and Expansion Microscopy Protocols to Explore the Topographic Organization of Oligodendrocytes in White Matter

Authors

• JC Combista
• TD Merson

Abstract

White matter in the central nervous system is characterized by a structured arrangement of repeated segments and regularly spaced glial rows, predominantly comprised of oligodendrocytes and solitary astrocytes, a structure initially described by Suzuki and Raisman in 1992. These glial rows have been postulated to play a crucial role in orchestrating the coordinated myelination of axons by oligodendrocytes. Building upon this foundation, our research delves into the intricate topography of myelin sheath formation by oligodendrocytes residing within these glial rows, which we term “linear arrays”. Our focus is specifically on the mouse corpus callosum, aiming to unravel the mechanisms orchestrating the coordinated myelination of axonal targets within white matter tracts.

To visualize the three-dimensional topography of the linear arrays in the corpus callosum, we are refining expansion microscopy and tissue-clearing techniques. Following protocol optimization, we intend to employ these methodologies to examine brain sections from transgenic mouse lines, including PLP-CreERT::RGBow mice, in which oligodendrocytes express one of six potential combinations of fluorescent reporter proteins following random recombination of the RGBow allele. Our aim is to investigate the hypothesis that oligodendrocytes within linear arrays myelinate a common set of axons in their vicinity that share a common function.

Upon elucidating the mechanisms governing the topographic organization of oligodendrocyte processes within white matter, we aim to correlate these findings with physiological functions of oligodendrocytes using electrophysiological methods in future studies. This integrative approach promises a comprehensive understanding of the intricate processes underlying white matter organization and function in the central nervous system.

Scientific Focus Area: Neuroscience

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