Radial Glial Neural Progenitors Regulate Nascent Brain Vascular Network Stabilization Via Inhibition of Wnt Signaling
(A–D) Patterns of vessel growth from E14.5 to E17.5. IB4 (in green) was used to stain growing vessels in the cortical plate (CP, outlined by pairs of white bars in A–D). A small number of vessels are observed at E14.5 (A), while increased numbers are observed at E15.5 (B) and E16.5 (C). By E17.5, the most prominent vessels run in the vertical orientation (D). (E–F) Quantification of vessel density (E) and branching frequency (F) in the cortical plate. Vessel branching frequency increases from E13.5 and peaks at E15.5 and E16.5. Subsequently, it drops dramatically at E17.5. By contrast, vessel density remains relatively stable after E15.5. (G–H″) Patterns of cortical plate blood vessels as visualized using an mTomato/mEGFP reporter, which, when driven by the neural-specific nestin-cre, expresses mEGFP (in green) in radial glia but mTomato (in red) in vessels at both E16.5 (G–G″) and E17.5 (H–H″). In contrast to E16.5, the vast majorities of vessels run vertically at E17.5. (I–J) Direct interactions between radial glia and ECs at E16.5 by 3-D reconstruction. ECs, pericytes, and radial glia were labeled with IB4 (in green) and NG2 (in blue) and GLAST (in red) antibodies, respectively. Cross-sections showed direct interactions between ECs and radial glia (arrows) despite significant pericyte coverage. (K–L) Direct interactions between radial glia and ECs were also observed at E16.5 by BLBP labeling of radial glia (in red). ECs were labeled by IB4 (in green). Cross-sections showed direct interactions between ECs and radial glia (arrows). Scale bar (in H″): 100 µm for (A–D) and (G–H″).