Double immunofluorescence of CD163 with fibrinogen. (a and b) Immunofluorescence for fibrinogen in the (a) occipital cortex of an AD case and (b) cingulate cortex of a PD case. Fibrinogen was found to exude from compromised blood vessels in both AD and PD cases, but to a lesser extent in the PD cases. Arrows point to compromised blood vessels where fibrinogen has leaked into the surrounding parenchyma. (c and d) Double immunofluorescence for CD163 (red) and fibrinogen (green) in the (c) frontal and (d) occipital cortex of AD cases. Presence of CD163 immunoreactive microglia at close proximity to areas of fibrinogen leakage in the parenchyma. This raises the possibility that CD163 immunoreactive microglia are a result of migration from the periphery. Astrocytes were also found to have fibrinogen immunoreactivity.