Epithelial tissues choroid plexus

Macrophage-like cells which morphologically resemble epiplexus cells and which are very abundant within the coimective tissue stroma and also between the epithelial cells of all choroid plexuses of Macaca mulatta, are thought to be monocytes (Merker 1972). 

It is well-established that Pb accumulates in the choroid plexus of himians as well as animals, suggesting that the choroid plexus is a primary target for Pb-induced neurotoxicity Behl et al. (2009) demonstrated that exposure to Pb results in a significantly increased accumulation of intracellular amyloid-p (APi o) hi rat choroid plexus tissues in mvo and in immortalized choroidal epithelial Z310 cells in intro. Several mechanisms may lead to an increased Ap level at the BCSFB a diminished expulsion of Ap molecules from the plexus cells to the extracellular milieu an increased uptake of Ap from the CSF, blood, or both an increased synthesis of Ap and/or a reduced metabolism or degradation of Ap. Pb-induced inhibition of the production of LRPl (a key intracellular Ap transport protein in the choroid plexus) may be responsible for the accmnulation of Ap, and may be a major risk factor for AD. 

The vascular barrier system in the brain consists of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barriers. There is another barrier, the brain-CSF barrier, between brain tissue and the CSF. The locations of these barriers are demonstrated in Figure i4.i [3]. The blood-brain barrier is the name for the wall of the cerebral microvessels in the brain parenchyma. At the surface of the brain parenchyma, microvessels running in the pia mater are called pial microvessels, which are often used as in vivo models for studying the BBB permeability. Owing to its unique structure that wiUbe discussed in the next section, the BBB maintains very low permeability to water and solutes. In the middle of the brain parenchyma, there are ventricular cavities (ventricles) filled with CSF secreted by the epithelial cells of choroid plexus [4]. The choroid plexus is a highly vascular tissue with leaky, fenestrated capillaries covered with ependymal epithelium, which has relatively tight junctions. The multiceU layer between the blood and the CSF in the choroid plexuses is called the blood-CSF barrier. 

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