Structural characteristics and barrier properties of the choroid plexuses in developing brain of the opossum (Monodelphis Domestica)

Abstract

The structural and functional development of the choroid plexuses, the site of the blood-cerebrospinal fluid (CSF) barrier, in an opossum (Monodelphis domestica) was studied. Marsupial species are extremely immature at birth compared with more conventional eutherian species. Choroid plexus tissue of each brain ventricle, from early stages of development, was collected for light and electron microscopy. During development, the choroidal epithelium changes from a pseudostratified to a cuboidal layer. Individual epithelial cells appear to go through a similar maturation process even though the timing is different between and within each plexus. The ultrastructural changes during development in the choroidal epithelial cells consist of an increase in the number of mitochondria and microvilli, and changes in structure of endoplasmic reticulum. There are also changes in the core of plexuses with age. In contrast, the structure of the tight junctions between epithelial cells does not appear to change with maturation. In addition, the route of penetration for lipid insoluble molecules from blood to CSF across the choroid plexuses was examined using a small biotin-dextran. This showed that the tight junctions already form a functional barrier in early development by preventing the paracellular movement of the tracer. Intracellular staining shows that there may be a transcellular route for these molecules through the epithelial cells from blood to CSF. Apart from lacking a glycogen-rich stage, cellular changes in the developing opossum plexus seem to be similar to those in other species, demonstrating that this is a good model for studies of mammalian choroid plexus development.

Expression of P2X receptors in rat choroid plexus

“…In a previous study, the presence of moderate expression of mRNA for P2Y 4 receptors was found in the adult rat choroid plexus [20], again suggesting that ATP may play a role in the function of the choroid plexus, although no direct evidence exists yet to support this speculation. Two types of epithelial cells, 'dark and light', have been reported in choroidal epithelial cells of several mammalian species [21][22][23][24]. It has been suggested that these differences in appearance of cells may represent different states of cell hydration, but the possibility that they may be fixation artifacts was also raised [21].…”

Review: Role of developmental inflammation and blood–brain barrier dysfunction in neurodevelopmental and neurodegenerative diseases

“…choroid plexuses soon after they first appear [22,23], indicating that both blood-brain barrier and bloodcerebrospinal fluid barriers are functional from very early in development (for recent reviews of the brain barriers see [8,24]). However, the structural and functional maturity of the brain barriers has been a matter of controversy for some time now and has recently been discussed elsewhere [8,24].…”

The transcription factor Otx2 regulates choroid plexus development and function

“…The ChPs are formed between embryonic day (E) 11 and 14 in the mouse, with the fourth ventricular (hindbrain) ChP differentiating first followed by the two lateral ventricular and later the third ventricular ChP (Dziegielewska et al, 2001). The ChPs acquire barrier, secretory and transport capacities shortly after formation (Møllgård et al, 1976;Ek et al, 2003;Johansson et al, 2005;Johansson et al, 2006;Liddelow et al, 2009;Ek et al, 2010). This early functionality and their localization inside the cerebral ventricles, together with their appearance during the period of neurogenesis, make them uniquely suited for influencing CSF composition and thereby regulating development of the neural stem cells that are in contact with the ventricle along the entire neuraxis (e.g.…”