(A) Schematic representation of intra-meningeal injection (IMI) of fluorescent dyes or lentiviral particles in the subarachnoidal space between the arachnoid (red/brown line) and pia mater (green line) of the meninges at the level of lambda.

(B–D) Sagittal brain section of a P0 mouse after IMI with fluorescein isothiocyanate (FITC)/dextran dye (B), carboxyfluorescein succinimidyl ester (CFSE)-labeled lentiviral particles (C) or LV-CherryRed (D) showing that at 1 hr (B and C) or 15 hr (D) post IMI, the labeling is confined to meninges and meningeal substructures, but undetectable in brain parenchyma. Inset in (C) shows a higher-magnification view of CFSE-labeled lentiviral particles before IMI (green, arrows).

(E) Brain distribution of CherryRed+ cells in meninges and ventricular and subventricular zone (VZ/SVZ) of the lateral ventricle and cortex at 15 hr, 24–48 hr, and 3–5 days after lentiviral IMI.

(F) Quantification of the fractional distribution of the CherryRed+ signal in meninges and meningeal substructures (M; gray bar), ventricular and subventricular zone (V; orange bar), and cortex (C; red bar) at 15 hr (n = 4), 24–48 hr (n = 4), and 3–5 days (n = 3) after IMI.

(G and H) Sagittal (G) and coronal (H) brain section of a mouse upon IMI with LV-CherryRed at P0 showing CherryRed+ cells in the upper cortical layers 3 weeks later. Inset in (G) represents a higher-magnification view of the boxed area.

(I) Three-dimensional reconstruction showing CherryRed+ (red) cell distribution at 30 days after IMI of LV-CherryRed in P0 mice.