Neural stem/progenitor cells (NPCs) overexpressing fibroblast growth factor 2 (FGF-2) have the distinct tendency to associate with the vasculature and establish multiple proliferative clusters in the perivascular environment after transplantation into the cerebral cortex. Strikingly, the vascular clusters of progenitor cells give rise to immature neurons after ischemic injury, raising prospect for the formation of ectopic neurogenic niches for repair. Here, we investigated the spatial relationship of perivascular clusters with the host vascular structures. FGF-2-GFP-transduced NPCs were transplanted into the intact somatosensory rat cortex. Confocal microscopic analysis revealed that grafted cells preferentially contacted with venules at sites with aquaporin-4-positive astrocytic endfeets and avoided contacts with desmin-positive pericytes. Electronmicroscopic analysis confirmed that grafted cells preferentially contact with astroglial endfeeds and only a minority of them reaches the endothelial basal membrane. These results provide new insights into the fine structure and anatomical relation of grafted FGF-2-transduced NPCs with the host vasculature.