Fig. 3

Light microscopic observation of white matter vacuoles in an autopsy case with SCA34. a Hematoxylin–Eosin (HE) staining of the frontal cortex showing vacuoles in the white matter (arrowheads) but few in the gray matter. WM and GM denote white and gray matter, respectively. b Vacuoles in the right superior cerebellar peduncle are shown. c A magnified view showing single vacuoles and adhered multiple vacuoles (arrowhead) (magnified from the rectangular area in a). Cells with swollen cytoplasm and round and bright nuclei, often accompanied by one or more similar adjacent cells (arrows in c and e), suggest that these vacuoles were derived from oligodendrocytes. d, e, f, and g Various forms of vacuoles in the cerebral white matter were observed. A thin septum was often seen between adjacent vacuoles (arrowheads in d and f). In some vacuoles, flattened nuclei were observed in the rim (arrows in g). h Oil red staining did not reveal lipid substance in vacuoles (arrowhead). i, Anti-MBP staining of thin rims and septum, suggesting that components of myelin surround the vacuoles (arrowhead). j, k, l Nuclei inside the rims of vacuoles were often Olig2-positive. m Confocal immunofluorescence microscopy using anti-Neurofilament H antibody (axonal neuronal protein, in red), fluoroMyelin (staining lipid contents of myelin, in green), and 4′,6-diamidino-2-phenylindole (DAPI) (nuclear staining, in blue). Arrows indicate the neuronal fibers, including myelin circumscribing a vacuole and an oligodendrocyte. Scale bar = 250 μm (a and b), 50 μm (c to g), 20 μm (h to m)