Fig. 3

SLYM encases the brain parenchyma from the upper spinal cord to the olfactory bulb region. (A) Sagittal section from a Prox1-eGFP mouse stained for GFP. GFP immunosignal forms a lamina covering the entire brain, delimiting the cisternal spaces. Colored insets are used to show high magnification images of different anatomical regions. The dashed line indicates the plane through foramen magnum separating the spinal cord (SP) from medulla oblongata (MO). (B) Black insert shows the rostral extension of the basal cistern (arrowheads). Note that the histochemical reactivity is attenuated corresponding to the median eminence (arrow). Cisterna interpeduncularis (CiIP) has been already analyzed in a previous publication (Møllgård, et al., 2023 [12], suppl. Fig. 3). (C) Green insert depicts the cisterna pontis (CiP), lining the basal CSF space. (D) Magenta insert shows a higher magnification view of SLYM, where individual GFP positive cells (arrowheads) seem to be partly covered by an inner cell layer to the left. (E) Orange insert shows the region of confluence of sinuses (CS) where the GFP signal is clearly visible (arrowheads), delimiting the cisterna tegmentalis (CiT). (F) Blue insert shows the superior cerebellar cistern (cisterna vermis), delimiting two CSF spaces adjacent to the cerebellum. The one-layered delicate SLYM membrane deviates between attachment to the skull and the cerebellar pial surface. (G) Blue insert depicts an adjacent section to panel F stained following omission of the primary (GFP antibody. The delicate unstained SLYM membrane is present but can barely be identified. Arrowheads are placed in the same positions in F and G. CB: cerebellum, ChP: choroid plexus, CiC: carotidand chiasmatic cistern, CiIP: cisterna interpeduncularis. CiP: cisterna pontis, CiI: cisterna tegmentalis, CM: cisterna magna, CS: confluence sinuum, M: mesencephalon, MO: medulla oblongata, P: pons, PG: pituitary gland, SP: spinal cord. Magnification is indicated by labelled bars on the individual figures