We developed a "pan-expansion" protocol that works well in brain tissue, using a ~20x iterative expansion compatible with pan-protein and lipid stains to reveal dense, nanoscale ultrastructure of neuronal circuits (~20 nm effective resolution) with a confocal microscope. (2/5)

Because this protocol retains proteins in the gel, it is natively compatible with antibody labeling, allowing localization of synaptic proteins, cell-type and subcellular markers with ultrastructural resolution, effectively a sort of “multicolor electron microscopy”. (3/5)

Indeed, we show that "pan-ExM" enables tracing of the thinnest neuronal wires (spine necks and thin axons) and can be scaled up to produce connectomes. Combining with antibody labeling enables “molecular connectomics”, which can unite cellular/molecular and systems understandings of the brain. (4/5)