Choroid plexus cerebrospinal fluid production

Milhorat, T.H., et al. 1971. Cerebrospinal fluid production by the choroid plexus and brain. Science 173 330. 

O Donnell ME, Duong V, Suvatne J, Foroutan S, Johnson DM (2005) Arginine vasopressin stimulation of cerebral microvascular endothelial cell Na-K-Cl cotransporter activity is VI receptor and [Ca] dependent. Am J Physiol Cell Physiol 289 C283-C292 Oshio K, Watanabe H, Song Y, Verkman AS, Manley GT (2005) Reduced cerebrospinal fluid production and intracranial pressure in mice lacking choroid plexus water channel Aquaporin-1. FASEB J 19 76-78... 

The second barrier separating the central nervous system from blood circulation is the choroid plexus or plexus choroideus. It is formed by a vascular sponge, which is surrounded by epithelial cells (ECs) and which is located within the ventricles ofthe brain. The actual barrier is formed by the epithelial cells and not by the interior capillary. One of the major functions of the choroid plexus is the production of cerebrospinal fluid (liquor). In addition, the epithelial cells secrete ions, peptides, nutrients, and vitamins [105]. 

The S-HTjc receptor has highest density in the choroid plexus on epithelial cells associated with production of cerebrospinal fluid (Razos and Palacios 1985]. 5-HT2C receptors are also found in the cingulate cortex, hippocam-... 

In addition, the epithelial cells of the choroid plexus facing the cerebrospinal fluid (CSF) constitute the blood-cerebrospinal fluid barrier (BCSFB). The BCSFB is also a significant area for exchange between the blood and the CSF. In rats the total calculated surface area of the choroid plexus is about 33% of that of the BBB [2]. In humans, based on the relative mass of the choroid plexus in comparison with the brain, the relative surface area of the choroid plexus may be in the region of 10% of that of the BBB. The CSF is secreted across the choroid plexus epithelial cells into the brain ventricular system [3] the remainder of the brain extracellular fluid (ECF) and the interstitial fluid (ISF) are secreted at the capillaries of the BBB themselves [4]. The ratio of fluid production from these sites is 40% 60%, respectively [5],... 

The choroid plexus are bags composed of epithelial cells that project into the ventricles and contain a capillary plexus (lohanson, 1988). The capillaries do not have barrier function and so produce an ultrafiltrate, w hich fills the bag. The epithelial cells have tight junctions and so prevent the ultrafiltrate fi om entering the ventricular space. Unlike the capillaries, the epithelial cells of the choroid plexus have a high rate of vesicular turnover, w hich is responsible for the production of the cerebrospinal fluid (CSF). How ever, the CSF is not an ultra-filfi ate, but a secreted substance. The choroid plexus also has many selective transport systems, some of w hich are specific to it or are enriched in comparison to the vascular BBB. 

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