Figure 1.

Microspheres move along arteries. The cranial window (black circle in (a)) was made to image branches of the MCA. (b) A typical image of two microspheres moving close to the vessel wall (indicated by the white lines). A capillary crosses the MCA branch (black lines). The majority of the microspheres were found close to the vessel wall, suggesting that the paravascular space is around 20 µm in width at this level of the vascular tree (c). Only a few microspheres were observed at larger distance, presumably in the subarachnoid space (SAS). Data are mean ± SEM. Scale bar represents 50 µm. *p < 0.05 and **p < 0.01.