Glial tangles in Pick's disease

In seven of nine patients with Pick's disease (PD), tau‐positive glial inclusions were observed. Coiled, wavy or globular shaped oligodendroglial fibrillary tangles (OFT) were found mainly in the cerebral white matter. However, thorn or corolla shaped astrocytic fibrillary tangles (AFT) were observed in the cerebral cortex. Three types of fibers were observed ultrastructurally in the OFT in the white matter. The first type was loose, fascicular and straight microfibrils measuring about 15 nm in diameter with a center core, which was observed in the coiled type OFT. The second type, observed in the wavy shaped OFT, was fibrils with about 200 nm periodic constrictions, the width was approximately 22 nm at the widest point and 11 nm at the constrictions. The third, observed in globular type OFT, was microfibrils measuring about 15 to 25 nm in diameter crossing at random. Astrocytic fibrillary tangles in the cortex were composed of 15 nm straight tubules. Our findings indicate that OFT and AFT are often present in classical PD and that the argyrophilic Pick bodies, OFT and AFT are distinct pathological structures occurring in different types of cells.