Thorn-shaped astrocytes: possibly secondarily induced tau-positive glial fibrillary tangles.
Argyrophilic and tau-positive abnormal structures occurring in glial cells are called glial fibrillary tangles. In the astrocyte, a conspicuous tau-positive structure is known to appear in progressive supranuclear palsy (PSP). In this report, another type of argyrophilic and tau-positive astrocytes is reported. The morphology of this new type is quite different from that of the previously reported tau-positive astrocyte in PSP and they are designated here as thorn-shaped astrocytes (TSA). TSA have an apparently argyrophilic cytoplasm with a few short processes and often have a small eccentric nucleus, whose appearance resembles that of a reactive astrocyte. Immunohistochemically, TSA are positive to anti-tau antibodies but are negative for ubiquitin. Simultaneous immunostaining revealed the coexistence of tau and glial fibrillary acidic protein epitopes in the same cytoplasm. Electron microscopically, bundles of 15-nm straight tubules were included in the cytoplasm together with abundant glial filaments. In the vicinity of a cluster of TSA, related structures of perivascular or subpial tau-positive linings, which correspond to astrocytic end-feet, are sometimes observed. In almost all cases, a few TSA are generally located in a confined area of subpial and subependymal regions. Although TSA appear to be intimately associated with some diseases, they are also found in a wide range of cytoskeletal disorders including the aged brain with neurofibrillary tangles. TSA are presumed to be a secondary induced product in relation to astrocytic reaction.
Ikeda
K
K
Department of Neuropathology, Tokyo Institute of Psychiatry, Setagaya-ku, Japan.
Akiyama
H
H
Kondo
H
H
Haga
C
C
Tanno
E
E
Tokuda
T
T
Ikeda
S
S
D000368:Aged; D000369:Aged, 80 and over; D001253:Astrocytes / Q000648:ultrastructure*; D003599:Cytoskeleton / Q000648:ultrastructure; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D016874:Neurofibrillary Tangles / Q000648:ultrastructure*; D009457:Neuroglia / Q000378:metabolism* / Q000648:ultrastructure*; D016875:tau Proteins / Q000378:metabolism*
D005904:Glial Fibrillary Acidic Protein; D016875:tau Proteins