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Development of the Choroid Plexus

Citation

Dziegielewska, KM and Ek, J and Saunders, NR, Development of the Choroid Plexus, Microscopy Research and Technique, 52, (1) pp. 5-20. ISSN 1059-910X (2001) [Refereed Article]

DOI: doi:10.1002/1097-0029(20010101)52:1<5::AID-JEMT3>3.0.CO;2-J

Abstract

Mammalian choroid plexuses develop at four sites in the roof of the neural tube shortly after its closure, in the order IVth, lateral, and IIIrd ventricles. Bone morphogenetic proteins and tropomyosin are involved in early specification of these sites and in early plexus growth. Four stages of lateral ventricular plexus development have been defined, based on human and sheep fetuses; these depend mainly on the appearance of epithelial cells and presence or absence of glycogen. Other plexuses and other species are probably similar, although marsupials may lack glycogen. Choroid plexuses form one of the blood-brain barrier interfaces that control the brain's internal environment. The mechanisms involved combine a structural diffusion restraint (tight junctions between the plexus epithelial cells) and specific exchange mechanisms. In this review, it is argued that barrier mechanisms in the developing brain are different in important respects from those in the adult brain, but these differences do not necessarily reflect immaturity of the system. Absence of a barrier mechanism or presence of one not found in the adult may be a specialisation that is appropriate for that stage of brain development. Emphasis is placed on determining which mechanisms are present in the immature brain and relating them to brain development. One mechanism unique to the developing brain transfers specific proteins from blood to cerebrospinal fluid (CSF), via tubulocisternal endoplasmic reticulum in plexus epithelial cells. This results in a high concentration of proteins in early CSF. These proteins do not penetrate into brain extracellular space because of "strap" junctions between adjacent neuroependymal cells, which disappear later in development, when the protein concentration in CSF is much lower. Functions of the proteins in early CSF are discussed in terms of generation of a "colloid" osmotic pressure that expands the ventricular system as the brain grows; the proteins may also act as specific carriers and growth factors in their own right. The pathway for low molecular weight compounds, which is much more permeable in the developing choroid plexuses, appears also to be a transcellular one, rather than paracellular via tight junctions. There is thus good evidence to support a novel view of the state of development and functional significance of barrier mechanisms in the immature brain. It grows in an environment that is different from that of the rest of the fetus/neonate and that is also different in some respects from that of the adult. But these differences reflect developmental specialisation rather than immaturity. © 2001 Wiley-Liss, Inc.

Item Details

Item Type:Refereed Article
Research Division:Medical and Health Sciences
Research Group:Neurosciences
Research Field:Central Nervous System
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Nervous System and Disorders
Author:Dziegielewska, KM (Dr Kate Dziegielewska)
Author:Ek, J (Mr Joachim Ek)
Author:Saunders, NR (Professor Norman Saunders)
ID Code:21503
Year Published:2001
Web of Science® Times Cited:122
Deposited By:Pathology
Deposited On:2001-08-01
Last Modified:2002-07-29
Downloads:0

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