Fig. 2

Enlarged perivascular spaces in animals with PTS. Normal appearing blood vessel in the spinal cord from a healthy control animal (a). Perivascular microcavities were identified in some blood vessels in PTS animals (white arrows) and were hypothesized as an early stage pathological process that leads to enlarged perivascular spaces (b, c). Dilated perivascular spaces were observed in the vicinity of cavities around all types of blood vessels in PTS animals; examples of enlarged perivascular spaces (black arrows) around venules (d), arterioles (e, f) and capillaries (g, h). A maximum radial width (MRW) measurement is shown around an enlarged perivascular space of a capillary (h). The ratio of MRW of the perivascular space to maximum vessel diameter (MVD) was significantly larger in PTS animals (n = 11) when compared to controls (n = 15): unpaired t-test, p < 0.0001 (i). A, astrocyte; L, lumen; M, macrophage; S, syrinx; *, basal laminae. Magnification: ×25,000 (a), ×5800 (b, h), ×10,500 (c, f), ×3400 (d), ×4600 (e), ×1450 (g). Scale bars: 0.2  µm (a), 2  µm (b, d, e, h), 1 µm (c, f), 5  µm (g)