Thorny astrocytes exhibit intense staining with anti-tau antibodies that tends to be restricted to the perinuclear cytoplasm and the proximal portions of the processes. This produces a characteristic spiked or thorny appearance. In our experience, they are found only in subpial and subependymal layers, although others have reported them in perivascular locations. They are profuse in PSP, but have been reported in other degenerative diseases and, rarely, in control brains. Image: a thorny astrocyte near the pial surface of frontal cortex from a PSP case. Immunostaining with antibody Tau-1, hematoxylin counterstain.

Reference: Ikeda, et al., 1995