Cisternal and subependymal localization of immune cells in the brain of PI rats. (A, B, C) The number of cisternal immune cells increases in PI rats (B, illustrated by the optic tract cistern at D11) in comparison to control (A) animals. Most of these cells are CD68+ monocytic cells (C). (D, E) In PI rats, leukocytes are also observed in a subependymal position. CD45+ immune cells at the level of the lateral (D) and third (E) ventricles are shown. Inserts in panel A and B show higher magnifications of immune cells. Scale bar, 50 μm. Dashed lines delimit cisterns (A, B, C) or ventricles (D, E). 3 V, third ventricle; CiOT, cistern of the optic tract; ep, ependyma; Hypo, hypothalamus; LVCP, lateral ventricle choroid plexus.