Microsphere embolism-induced damage to microvessels caused a focal response in neighboring microglial cells. (A) Changes in metabolic activity of glucose 168 h after microsphere embolism (ME) imaged on the microPET scanner. Images were taken from the same scan and reconstructed using the maximum a posteriori probability algorithm. Arrows indicates the ipsilateral hemisphere of rat brain. (B) Fluorescent staining with anti ED1 antibodies indicates predominant microglia activation beside the region blocked by microspheres (arrow). A number of activated microglia appeared to associate with a more distal region of the vessel as shown in the longitudinal section (a) and cross section (b). (C) Activated microglia were also found surrounding microsphere region (outlined in red), is shown in a series of XZ reconstructions. DAPI counterstaining indicates cell nuclei (blue). Scale bar = 50 μm. ME, microsphere embolism.