Anchorage densities associated with hemidesmosome-like structures in perivascular reactive astrocytes

Electron microscopical examination of devastated and reticular gliosis-replaced areas of two human brains revealed novel anchorage densities (ADs) associated with hemidesmosome-like structures (HDLSs) in perivascular astrocytes; the densities, 200-300 nm away from the cell membrane overlying the basal lamina, ran parallel to the membrane. The subplasmalemmal ADs usually received fibrils from the main stream of the deeply located glial fibrils, and sent isolated 13- to 16-nm fibrils roughly perpendicularly to the unusually prominent and frequently continuous HDLSs on the inner leaflet of the cell membrane, undercoated by a thickened basal lamina. The variable profiles of the ADs indicated that they were cell membrane-connected sheets or meshes that were virtually completely composed of bundles of glial fibrils intercrossing at variable angles or running roughly parallel to one another. All these findings suggest that the ADs may provide a significant support to the cell membrane facing the perivascular space.