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FIG 4. MR Imaging and histologic staining of marmoset HWM-2.
A, Two MR slices are presented for the preterminal PD- (2800/22/2), T2- (2800/110/2), and post T1-weighted contrast-enhanced (400/19/3) imaging sequences. LFB-stained histologic sections are below the corresponding MR brain slice. This marmoset had a clinical grade of 3 because of a paraparesis resulting presumably from lesions affecting the spinal cord motor tracts. A demyelinated lesion on the LFB-stained slice 1 on the right side of the corpus callosum (large arrowhead) matches the centrally hypointense and peripherally hyperintense lesion on the corresponding PD-weighted image and the enhancement on the postcontrast T1-weighted scan. This lesion measured 1 mm on the MR scan and histologic features of this lesion are shown in figure 4B. A smaller demyelinating lesion present on the left side of the corpus callosum of LFB-stained slice 1 (small arrowhead) is seen as a hyperintense area on the PD-weighted image and as an enhancing lesion on the postcontrast T1-weighted image (small arrowhead). This lesion was 0.5–0.75 mm in size. The enhancing corpus callosal lesion, although already demyelinated, has a persistent inflammatory infiltrate possibly representative of a chronic active lesion. The enhancing properties on the postcontrast T1-weighted images may reflect either active cytokine release mediating a BBB breakdown or permanent BBB integrity damage. The MR and clinical scores for this animal are presented in figure 1, Panel B. (Scale bar equals 5 mm)
B, The top left panel shows an H&E-stained section (magnification, 100x [top left]) of the right corpus callosal lesion (fig 4A, slice 1 [large arrowhead]) that has a dense perivascular mononuclear inflammatory cell collection and moderate infiltration of the surrounding parenchyma. In the top right panel, the LFB-stained section (magnification, 100x [top right]) of the same field reveals demyelination throughout the involved area. In the bottom panels, the bodian silver—stained section (magnification, 100x [bottom left]; magnification, 400x [bottom right]) was used to confirm that the axonal processes were relatively spared even when there was pronounced demyelination.
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