Immunohistology of the area postrema (AP) during EAE. MECA-32+ capillaries within the AP stain positive for ICAM-1 and VCAM-1 during EAE. A large number of CD45+ cells can be detected within the AP, which are associated with the microvessels (e.g. filled arrows) or localized within the parenchyma (e.g. open arrows). The majority of those are macrophages/microglial cells as determined by positive immunostaining for F4/80 and Mac-1. Note, whereas staining for Mac-1 can be detected on cells throughout the AP, staining of F4/80 is only seen on perivascular cells. Immunoperoxidase, hematoxylin counterstain. Bar = 100 μm. This result was observed in at least 10 individual stainings.