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  • 1
    Electronic Resource
    Electronic Resource
    Localization of aldose reductase and sorbitol dehydrogenase in the nervous system of normal and diabetic rats (1981)
    Springer
    Acta diabetologica 18 (1981), S. 373-381 
    Details
    ISSN: 1432-5233
    Keywords: Aldose reductase ; Diabetes ; Histochemistry ; Nervous system ; Sorbitol dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intraneuronal accumulations of sorbitol and fructose have been postulated to predispose the nervous system to the cerebral edema associated with the treatment of diabetic ketoacidosis. In the present study, the enzymes of the pathway for the production of sorbitol and fructose, aldose reductase and sorbitol dehydrogenase, were localized histochemically in brain, spinal cord and sciatic nerve. Enzyme activity was limited to the choroidal epithelium, ependymal cells, and pia mater in normal, 2- and 10-week streptozotocin diabetic and vehicle-treated rats. Sorbitol dehydrogenase activity was located in blood vessels and perineurium of the sciatic nerve in these groups of rats. Comparison of diabetic and vehicle groups did not demonstrate any alteration in the activity of either enzyme in the central nervous system. However, there was a decrease in sorbitol dehydrogenase activity in the blood vessels in the sciatic nerve in 50% of the 10-week diabetic rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042822
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Circulation of cerebrospinal fluid in the bullfrog, Rana catesbiana (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 389-403 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to demonstrate features of the cerebrospinal fluid (CSF) path in the amphibian, 2-6 m̈l of either Evans Blue-albumin (EBA) or ferrocyanide were injected into the ventricular system of anesthetized bullfrogs. The animals were sacrificed 1 to 135 minutes after injection by either quick freezing (EBA injections) or fixative perfusion (ferrocyanide injections). The contents of the cranial and vertebral cavities were then examined grossly and histologically for distribution of the tracers. In all animals, the tracers were seen throughout the ventricular cavity and in the subarachnoid space surrounding the caudal hindbrain. The site of communication between these two fluid spaces was the posterior tela of the hindbrain. Within this tela, “pores” were found between groups of pavement-like ependymal cells. In many animals, tracer was also observed in the vertebral subarachnoid and epidural spaces, adjacent to spinal nerve roots. In three EBA-injected animals, this tracer was also seen in the subcardinal lymph spaces. These findings suggest that the subarachnoid space in the bullfrog communicates functionally with the ventricular system by way of specialized “pores” in the posterior tela of the hind-brain. There is also indication of movement of fluid within the subarachnoid space which is predominately caudal in direction, with a primary absorptive path for CSF that consists of a perineural route to the lymphatic system.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091940306
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fine structure of the rhombencephalic tela of the bullfrog, Rana catesbeiana (1979)
    Springer
    Cell & tissue research 202 (1979), S. 479-491 
    Details
    ISSN: 1432-0878
    Keywords: Ependyma ; Ultrastructure ; Posterior tela choroidea ; Rhombencephalon ; Rana catesbeiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The posterior rhombencephalic tela choroidea of the bullfrog was examined by electron microscopy. This membrane, the pia-ependymal roof of the caudal hindbrain, contains a large central region characterized by cuboidal ependymal cells which surround sizable microscopic apertures — the interependymal pores. Ultrastructurally ependymal cells of this area are characterized by infrequent apical microvilli and cilia. They contain irregularly shaped nuclei and few cytoplasmic organelles that are largely apical in position. The most striking feature is an abundance of cytoplasmic filaments forming an extensive cytoskeleton. Laterally these cells are joined by numerous elaborate desmosomes. The majority of the ependymal cells have a basal lamina consisting of single, double, or triple laminae lying parallel to the basal plasma membrane. Several unusual specializations are seen at the margins of the interependymal pores. The ependymal cells have lateral cytoplasmic processes that form the actual border of each pore. These processes originate from the apical surface of the cell and partially enclose an elaborate network of basal lamina associated with the interependymal pores. These findings demonstrate microscopic apertures in the roof of the fourth ventricle in the bullfrog that are associated with an unusual form of supportive ependyma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220439
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Arachnoid mater of the bullfrog, Rana catesbeiana (1984)
    Springer
    Cell & tissue research 236 (1984), S. 693-697 
    Details
    ISSN: 1432-0878
    Keywords: Intermediate filaments ; Microtubules ; Caveolae ; Bullfrog ; Arachnoid mater ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the bullfrog, the meninges surrounding the central nervous system include an arachnoid mater that contains layers of cells with abundant intermediate filaments (IFs) having unique organizational characteristics. This membrane contains an inner lamina of cells that resemble fibroblasts and an outer lamina of flattened cells that are almost filled with IFs. The IFs of the outer arachnoid are arranged in compact, arching bundles that lie parallel to the outer surface of the central nervous system. Thus, sections cut tangentially to the membrane reveal bending of filament bundles, whereas transverse sections do not. In some cells bordering the subdural space, bundles of filaments are organized into highly-ordered spiral arrays. Attachments to the numerous desmosomes and, apparently, to the nuclear envelope suggest anchoring of cytoplasmic structures by the IF system. Microtubules occur primarily near the plasma membrane and the nucleus. Numerous caveolae also are associated with the plasma membrane. The unusual abundance, organization, and cytoplasmic relations of IFs in the bullfrog arachnoid suggest that this membrane may serve as an important model for study of fundamental cytoskeletal relations and function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217240
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Fine structure of the lateral areas of the rhombencephalic tela of the bullfrog, Rana catesbeiana (1980)
    Springer
    Cell & tissue research 211 (1980), S. 449-463 
    Details
    ISSN: 1432-0878
    Keywords: Ependyma ; Choroid plexus ; Leptomeninges ; Ultrastructure ; Bullfrog ; Tela choroidea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lateral areas of the rhombencephalic tela of the bullfrog contain long, irregular islands of ependymal cells that are similar in fine structure to the epithelium of the rhombencephalic choroid plexus. These cells are characterized by apical microvilli, numerous mitochondria and pinocytotic vesicles, and basal infoldings of the plasma membrane. Dorsally a basal lamina and varying amounts of collagen occur. The pia mater associated with this ependyma includes two cell types. Fibroblast-like, loosely arranged cells without organized junctions line the subarachnoid space. The most abundant cells of the pia in this area, however, contain numerous intermediate filaments and frequent desmosomes. Caveolae lie along their plasma membranes. Closely organized sheets of similar filament-containing cells are also seen in the arachnoid mater of this animal. These findings demonstrate ependymal cells in the lateral areas of the rhombencephalic tela of the bullfrog that have the essential features of choroid plexus epithelium, with ultrastructural characteristics that suggest transport function. They are, however, usually separated from neighboring, nonfenestrated vessels by several layers of leptomeningeal cells joined by desmosomes. The relationship between structure and function of these cells is enigmatic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234399
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    Paper (German National Licenses)
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