Figure 2.

CPM lesions with loss of AQPs. (a) The demyelinated lesion in the central basis pontis(e-h) is heavily infiltrated with activated macrophages (KiM1P, scale bar = 5 mm); (b) Higher magnification of an area of macrophage infiltration (KiM1P, scale bar = 500 μm) also shows (c) relative myelin preservation (PLP, scale bar = 500 μm), (d) loss of AQP4 (AQP4, scale bar = 500 μm), (e) loss of AQP1 (AQP1, scale bar = 500 μm), but (f) preserved GFAP immunoreactivity (GFAP, scale bar = 500 μm); Despite preservation of myelin, the presence of macrophages containing myelin degradation products both in the (g) gray matter (PLP, scale bar = 50 μm) and (h) white matter (PLP, scale bar = 50 μm) is consistent with active demyelination; The normal perivascular distribution of (i) AQP4 (AQP4, scale bar = 50 μm) and (j) AQP1 (AQP1, scale bar = 50 μm) is lost, but (k) small GFAP-immunoreactive astrocytes with short processes are still present in lesions; upper inset shows such an astrocyte in close contact with two macrophages; lower inset shows a macrophage containing GFAP + degradation products (GFAP, scale bar = 50 μm, upper inset scale bar = 25 μm, lower inset scale bar = 12.5 μm); (l) Axons are preserved, but the presence of axonal swellings (arrows) indicates axonal injury (NF, scale bar = 50 μm); (m) Neurons are relatively well preserved (HE, scale bar = 50 μm); (n) The lesion also contains mild parenchymal and perivascular T-cell inflammation (CD3, scale bar = 50 μm); (o) Apoptotic oligodendrocytes (arrowheads) are present (PLP, scale bar = 50 μm); (p) Rosenthal fibers are also present (HE, scale bar = 100 μm).