To measure vasogenic edema, the volume of anti-rat IgG positive region in PC was estimated according to the formula based on the modified Cavalieri method: V = Σa × tnom × 1/ssf, where a is area of the region of the delineated subfield measured by AxioVision Rel. 4.8 software, tnom is the nominal section thickness (of 30 μm in this study), and ssf is the fraction of the sections sampled or section sampling fraction (of 1/6 in this study).