Document Detail


Disruption of proteoglycans in neural tube fluid by beta-D-xyloside alters brain enlargement in chick embryos.
MedLine Citation:
PMID:  9845201     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Following neurulation, the anterior end of the neural tube undergoes a dramatic increase in size due mainly to the enlarging of the brain cavity. This cavity is filled with so-called neural tube fluid (NTF), whose positive pressure has been shown to play a key role in brain morphogenesis. This fluid contains a water-soluble matrix, rich in chondroitin sulfate (CS), which has been proposed as an osmotic regulator of NTF pressure genesis. The purpose of the present study is to observe the influence of CS on NTF osmolality and its relation to NTF hydrostatic pressure and brain expansion. NTF was obtained by means of microaspiration from the mesencephalic cavity of chick embryos. The osmolality of NTF between H.H. stages 20 and 29 was measured on the basis of its cryoscopic point. CS synthesis was disrupted by using beta-D-xyloside and the induced variations in brain volume were measured by means of morphometry. We also measured the variations in NTF osmolality, hydrostatic pressure, and the concentration of CS and sodium induced by means of beta-D-xyloside. Our data reveal that, at the earliest stages of development analyzed, variations in NTF osmolality show a characteristic pattern that coincides with the developmental changes in the previously described fluid pressure. Chick embryos treated with beta-D-xyloside, a chemical that disrupts CS synthesis, displayed a notable increase in brain volume but no other apparent developmental alterations. Morphometric analysis revealed that this increase was due to hyperenlargement of the brain cavity. Beta-D-xyloside brings about specific changes in the biochemical composition of NTF, which entails a large increase in CS concentration, mainly in the form of free chains, and in that of sodium. As a result, the fluid's osmolality and brain intraluminal pressure increased, which could account for the increase in size of the brain anlage. These data support the hypothesis that the intraluminal pressure involved in embryonic brain enlargement is directly dependent on NTF osmolality, and that the concentrations of CS and its associated microions could play a key role in the regulation of this process.
Authors:
M I Alonso; A Gato; J A Moro; E Barbosa
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Anatomical record     Volume:  252     ISSN:  0003-276X     ISO Abbreviation:  Anat. Rec.     Publication Date:  1998 Dec 
Date Detail:
Created Date:  1999-02-04     Completed Date:  1999-02-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370540     Medline TA:  Anat Rec     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  499-508     Citation Subset:  IM    
Affiliation:
Departamento de Anatomía Humana, Facultad de Medicina, Valladolid, Spain.
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MeSH Terms
Descriptor/Qualifier:
Animals
Brain / drug effects,  embryology,  pathology*
Cerebrospinal Fluid / drug effects,  metabolism*
Chick Embryo
Chondroitin Sulfates / metabolism*
Glycosides / toxicity*
Hypertrophy
Morphogenesis / drug effects
Neurons / ultrastructure
Osmotic Pressure / drug effects
Chemical
Reg. No./Substance:
0/Glycosides; 2001-96-9/4-nitrophenyl beta-D-xyloside; 9007-28-7/Chondroitin Sulfates

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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