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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 213 (1980), S. 81-94 
    ISSN: 1432-0878
    Keywords: Interlamellar tight junctions ; Central myelin ; Myelogenesis ; Optic nerve ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The process of myelination in the central nervous system (CNS) of the rat (optic nerve) was studied with the freeze-fracturing technique and ultrathin sectioning to obtain information on the developmental mechanisms of interlamellar tight junctions. Using a tilting cartridge for analysis of thin sections, it could be demonstrated that during the initial phase of wrapping a tight junction formation develops between the joining tips of the oligodendrocytic process. In tannic acid-stained samples these junctions appear as typical quintuple-layered membrane fusions, while in potassium permanganate-stained material membrane thickenings between the apposing glial tips are prevalent. The latter configuration represents the characteristic feature of the so-called radial component of central myelin. Using the freeze-fracturing technique, a biphasic mode of the myelinic tight junction assembly was detected. It is suggested that tight junctions represent a prerequisite of the myelination process.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 193 (1992), S. 152-163 
    ISSN: 0002-9106
    Keywords: Cerebral endothelium ; Development ; Immunocytochemistry ; Rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A constant supply of blood-borne glucose is vital to cerebral metabolism. Although transport of glucose into the nervous tissue, effectively separated from the blood by a functional barrier (the blood-brain barrier, BBB), is one of the essential properties of the cerebral endothelium, little is known about its metabolic regulation and developmental expression in the BBB. In this study we provide evidence by immunocytochemistry that the pattern of the brain endothelial glucose transporter in rat brains (BBB-GT), immunologically homologous with the human hepatoma (G2), human erythrocyte transporter (Glut 1), changes with BBB maturation. While the neuroepithelium at embryonic days 12 and 13 shows a high incidence of immuno-detectable BBB-GT, vascularisation of the cerebral anlage and subsequent development of vascular tightness, as evidenced by intravascularly applied horseradish peroxidase and fluorescinated dextrans, is accompanied by a significant reduction BBB-GT expression in neuroepithelial cells and confinement of BBB-GT expression to the cerebral endothelium. Immunoblots and Northern blots of embryonic brain homogenates corroborate this change in BBB-GT expression in the brain anlage at the time of BBB maturation. However, low molecular weight glucose transporters, presumed to be of non-endothelial origin, are less dramatically reduced. The development of BBB tightness, therefore, seems to play a pivotal role in the pattern of BBB-GT expression during brain differentiation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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