Figure 8

Proposed path for the transport of Gd-albumin tracer (black arrows) infused into the lateral ventricle. Tracer infused into the lateral ventricle reaches the subarachnoid space (SAS) either through the PVS in the parenchyma around it or through the CSF macro circulation in the ventricular system. A portion of the tracer in the SAS drains into the cribriform plate and superior sagittal sinus (SSS), while the rest is transported back into the brain parenchyma through PVS surrounding the blood vessels (green lines) in the brain surface. The PVS surrounding these blood vessels eventually join the macro CSF circulation in the ventricular system. Solute removal from the parenchyma could be facilitated by constant exchange between ISF in the parenchyma and CSF in the PVS by diffusion. Tracer also diffuses from the ventricles and SAS into the adjacent parenchyma (not shown). Arrows along PVS indicate possible directions of transport into and out of the brain. Abbreviations: LV - lateral ventricle, 3 V - third ventricle and 4 V - fourth ventricle.