We describe the presence of tau protein‐positive argyrophilic meshwork structures in the cerebral corticomedullary junctions of three patients with progressive supranuclear palsy (PSP). Meshwork structures are composed of fine, winding fibrils, partly connected to coiled inclusions in oligodendrocytes, and are present on neurofilament protein‐positive axons. The novel abnormal structures are numerous in the middle frontal and precentral gyri, and at the ultrastructural level they are present mainly in the outer myelin sheath. Our results suggest that the unusual meshwork structures are formed in processes of oligodendroglia in the cerebral cortex. Further study of well characterized cases is required in order to determine the significance of these structures in cerebral cortical functions in patients with