Fig. 1

Pericyte morphology and relationships within the NVU. a, b Scanning electron microscope images of 14-day-old chick embryo microvessels, showing in a primary (red arrow) and secondary (red arrowheads) pericyte processes and in b their highly indented and interdigitated finger-like processes (red arrows) [from [5] with permission]. c Dorsal wall of the telencephalic vesicles (forebrain, future neocortex) of an 18-week-old human fetus, GFAP⁺ (glial fibrillary acidic protein) radial glia fibers and a pericyte coverage NG2 2164C3⁺, the latter shows finger-like processes (arrows); note the very fine perivascular processes of OPCs (arrowheads). d A schematic representation showing NVU components: ECs, PCs, perivascular astrocytes, vessel-associated microglial cells, OPCs/NG2-glia, macrophages, nerve fiber terminal [from [13] with permission]. PCs, embedded in the vessel basal lamina (here not shown) are the cells closest to the endothelium and display a variety of extensive contacts on their abluminal surface, in particular the relation with astrocytes and OPCs/NG2-glia [10]. e Astrocyte-pericyte relations are shown by glutamine synthetase (GS), confined within the astrocyte body (arrow) and in perivascular endfeet (arrowheads), most of which are in contact with CD248⁺ PCs rather than, directly, with ECs. Scale bars a, b 1 µm; c 20 µm; e 10 µm