To visualize gene expression in a thick section of brain tissue with various cell types, RNA targets (top) are amplified to create multiple cDNA copies, each containing a barcode specific to the particular gene.
Acrylamide is then added to the tissue and cross-linked to the cDNA amplicons.
From the resulting hydrogel, fats and proteins are removed to leave a clear tissue within which the barcodes can be sequenced.
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