Caspase‐3 immunoreactivity associated with abnormal astrocytes in CADASIL. Caspase‐3 was frequently found in abnormal type B cells with large cell bodies and some retracted processes but not in normal astrocytes in either CADASIL or control subjects. (A–B) Perivascular immunoreactivity of Caspase‐3 was noted in deep WM of a CADASIL (R133C mutation) subject. Some astrocytes within the WM parenchyma were also observed in CADASIL (C) but there was no Caspase‐3 immunoreactivity in controls (D–F). Magnification bar = 50 μm in A and D, 25 μm in B, C, E, and F, and in insets = 5 μm (B and C).