Fig. 1

Hic1 identifies mesenchymal cells in the CNS, including in the CP and PG. A Overview of the Hic1^CreERT2; Rosa26^{LSL−tdTomato} labelling strategy. In this genetic background, tamoxifen administration leads to the indelible labeling of Hic1⁺ cells with tdTom. B Schematic cross-section of the mouse hindbrain, that highlights regions of abundant tdTom⁺ cells within the 4th ventricle CP and PG. Anatomical orientation is shown, D, dorsal; V, ventral; R, rostral; C, caudal. C Sagittal section of the hindbrain showing tdTom⁺ cells (red) within the 4th ventricle CP and PG. Samples were collected at 10 days post-TAM. D Enumeration of tdTom⁺ cells taken from sagittal sections of the midbrain (Mb), anterior PG (aPG), posterior PG (pPG) and 4th ventricle CP per total DAPI⁺ nuclei. E Representative sections of sagittal sections of the 4th ventricle CP and PG showing perivascular localization of tdTom⁺ cells in relation to the CD31⁺ endothelium and the laminin-containing extracellular matrix. F Representative sagittal sections of the 4th ventricle CP and cerebrum from Hic1^CreERT2; Rosa26^{LSL−tdTomato}; Pdgfra^H2B−EGFP mice. Red arrowheads represent singly tdTom⁺ cells, green arrowheads indicate singly EGFP⁺ cells and yellow arrowheads represent doubly positive cells. G Quantification of tdTom and GFP doubly positive cells in the indicated regions. H Co-localization of tdTom⁺ with GFP (Pdgfra^H2B−EGFP) and endogenous IgG reveals an abundance of doubly positive cells in the permeable CP and PG. I High magnification insets from dotted squares shown in H for CP and PG. Red arrowheads represent singly tdTom⁺ cells, green arrowheads indicate singly EGFP⁺ cells and yellow arrowheads represent doubly positive cells