|
FIG 3. Imaging studies and histopathologic analysis of MP4–2 marmoset.
A, PD- (2500/20/2), T2- (2500/80/2), pre- and postcontrast T1-weighted images (450/13/4) (top to bottom, respectively), and the difference (post- minus precontrast T1-weighted) images are presented for marmoset MP4–2, for weeks 2.5, 4, and the 15-week terminal scan after EAE induction (left to right, respectively). The corresponding clinical scores were 2 for ataxia (week 1), 1 for weak right-hand grip (week 2), and 2 for slight ataxia (week 4). The clinical and MR scores are shown in figure 1, panel D. Little correlation existed between the MR-revealed lesions and clinical scores in this animal except for the lesion on the left side of the brain (week 2.5) and the concomitant right upper extremity weakness. A large enhancing lesion is seen in the left periventricular region, corresponding to a lesion in the same area on the T2- and PD-weighted scans at 2.5 weeks (arrowheads). The degree of enhancement can be appreciated in the difference image. By week 4 the lesion was no longer enhancing, but was visible on the PD- and T2-weighted images. By week 6 (not shown), and on the terminal scan, the lesion is no longer visible on the PD- or T2-weighted scans. The disappearance of this lesion corresponds to sparse histopathologic visibility in the anatomic region of the brain. Initially the lesion, although large in size, either did not progress to the point of demyelination or represented an area of remyelination. The only lesion present on histologic slices in the area of the large MR-revealed lesion at 2.5 weeks is minimally visible on the whole-brain mounts in figure 3B, and at higher-power magnification in figure 3C. (Scale bar equals 5 mm)
B, Luxol fast blue stained coronal section confirms that there is no demyelination. A small perivascular cuff (arrow) was the only lesion in this anatomic region located after multiple histology sections were taken through this block of brain tissue. This whole brain mount of marmoset MP4–2 corresponds to the terminal coronal scan in figure 3A and to the higher magnifications of this lesion (arrow) in figure 3C.
C, A single perivascular cuff of inflammatory cells is found at high magnification on the H&E-stained section (magnification, 400x [left]). The LFB-stained section (magnification, 400x [middle]) reveals intact myelin, and the bodian silver—stained section (magnification, 400x [right]) reveals intact axonal processes surrounding the only inflamed vessel. This lesion corresponds to the area where a large WM lesion was present at 2.5 weeks in figure 3A (arrow) and to the lesion present on the whole-brain mounts in figure 3B (arrow).
|