Analysis of myelin debris clearance in the cerebral WM of TgPAC-Notch3
mice. (A-B) Sections of corpus callosum (delineated by a dashed line) immunostained with anti-Iba-1 antibody showing comparable labeling patterns in the control (A) and TgPAC-Notch3R169C
(B) mice. (C-D) Sections of corpus callosum immunostained with anti-CD68 antibody showing an increased labeling and presence of microglial aggregates (arrows) in TgPAC-Notch3R169C
(D) compared to control (C). (E) Sections of corpus callosum labeled with both SMI94 (red, myelin debris) and Iba-1 (green, microglia) showing two myelin debris contacted and/or internalized by microglial cells and processes (white arrowheads) while many others are not (empty arrowheads). (F) Electron micrograph of a microglial cell (colored in brown) containing a whorl of degenerating myelin (colored in blue) and two other inclusions of phagocytic material (colored in green). (G-H) Diagrams showing that the area of total microglia (Iba-1) is comparable between control (n = 4) and TgPAC-Notch3R169C mice (n = 6) (G), whereas the area of reactive microglia (CD68) is slightly, but significantly larger in TgPAC-Notch3R169C (n = 6) compared to control mice (n = 4) (H). (I-J) Diagrams showing the % of myelin debris contacted or internalized by a microglial cell as determined on confocal images (I) or electron micrographs (J) in 20-month-old TgPAC-Notch3R169C mice (n = 4). Scale bar represents 75 μm (A-D), 10 μm (E) and 2 μm (F).