Fig. 1

Large CSF tracers primarily circulate within the neonatal arachnoid and pia maters and not the dura. A Schematic of regions shown in B–D. B–D, Representative histology of decalcified skulls and the underlying meninges and parenchyma over the cortex (B), inferior colliculus (C), and cerebellum (D) showing minimal large CSF tracer (magenta) distribution through the pericranium, skull, and dura mater, but widespread distribution within the arachnoid and pia maters 4 h after 15-nm gold nanoparticle (AuNP) injection into the right lateral ventricle of P7 rats. There was also limited AuNP influx into the parenchyma. The subarachnoid space (SAS) is collapsed post-mortem and differentiation between layers was primarily based on tissue morphology. scalebars = 50 µm. E Quantification of the thickness of the midsagittal dura over the longitudinal fissure, the inferior colliculus (IC), and cerebellum (Cb). Data are mean ± SD, n = 3 per group; One-way ANOVA with post-hoc Tukey. F Representative X-ray microtomography (XRM) image showing high amounts of AuNP enhancement within the arachnoid mater (AM), pia mater (PM), and SAS, with less enhancement in the dura mater (DM). There was minimal enhancement in the lumen of the transverse sinus (TS) and parenchyma (P). scalebar = 500 µm. G, H Quantification of the percent change in mean intensity increase of 15-nm AuNPs in the dura, arachnoid, and pia maters (G) and the pia mater and parenchyma (H) compared to the background XRM signal. Data are mean ± SD, n = 3 per group; G One-way ANOVA with post-hoc Tukey. H Unpaired, two-tailed t-test All data are representative of 3 rodents