Morphological analysis of CP compartments following immunization. CP epithelium was stained with polyclonal antibody to pan-cytokeratin (FITC, green), and CP stromal capillaries were immunostained with monoclonal anti-CD31 antibody (red). A CD45 antibody was used to stain for any leukocytes present within the CP (blue). Confocal microscopy z-stack images of thick (60 μm) frozen sections of the CP were acquired, and three dimensional rendering was performed using Imaris image analysis software. Shown are rendered images of the CP from all three treatment conditions (MOG-CFA/PTX day 15 p.i., CFA-PTX day 15 p.i. and Naïve), revealing swelling of the stromal capillaries (arrows) following both immunization protocols. The left side shows leukocyte and capillary staining, emphasizing the distended capillary diameters. The right side is a composite of leukocyte, capillary, and epithelial staining. Mean capillary diameter ranges for each group were determined using the Filament tracer module in Imaris. The choroidal epithelium appears unaltered by immunization. ‘p’ indicates brain parenchymal region. Scale: 20 μm.