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  • 1
    Electronic Resource
    Electronic Resource
    Production of lymphoid tissue in the rat brain by implants containing phytohemagglutinin (1975)
    Springer
    Acta neuropathologica 31 (1975), S. 71-84 
    Details
    ISSN: 1432-0533
    Keywords: Lymphoid Tissue ; Plasma Cells ; Brain Implants ; Phytohemagglutinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Large numbers of plasmacytes and lymphocytic cells develop at the tip of miniature pipettes containing phytohemagglutinin (PHA) implanted into the brain of adult Lewis rats. The accumulation of lymphoid elements is present in tissue exposed to PHA for 1 week, and it persists in animals which were allowed to survive up to 10 weeks. It did not occur around control or non-active implants. Lymphoid cells usually serve as a morphologic index of immune mediated phenomena, but no evidence was seen in the present study to indicate that they produce damage to axons, dendrites or glial cells of the central nervous system despite direct contact with them. Plasma cells in the brain appear to develop from “dark” cells resembling lymphocytes that migrate into the central nervous system from reactive lymphoid tissue near the tip of the implant. Nerve, glial and subependymal cells do not respond with mitogenic activity to PHA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696888
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  • 2
    Electronic Resource
    Electronic Resource
    Histopathological evaluation of materials implanted in the cerebral cortex (1978)
    Springer
    Acta neuropathologica 41 (1978), S. 145-155 
    Details
    ISSN: 1432-0533
    Keywords: Cerebral cortex ; Brain implants ; Reactivity ; Toxicity ; Biocompatability ; Neuroprostheses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Histopathological changes of the cerebral cortex in response to small, penetrating metal and non-metal implants were analyzed by means of light and electron microscopy. The needle-shaped implants were left in place during all stages of histological preparation and embedded in plastic together with the cortex. Changes of the brain-implant boundary were classified as non-reactive, reactive, or toxic, according to the reactive cellular constituents. Among the non-reactive materials were several plastics and metals such as aluminum, gold, platinum, and tungsten. The boundary of these implants displayed little or no gliosis and normal neuropile with synapses within 5 μm of the implant's surface. The boundary of reactive materials such as tantalum or silicon dioxide was marked by multinucleate giant cells and a thin layer (10 μm) of connective tissue. Toxic materials such as iron and copper were separated from the cortical neuropile by a capsule of cellular connective tissue and a zone of astrocytosis. Cobalt, a highly toxic material, produced more extensive changes in the zones of connective tissue and astrocytes. These results indicate that a variety of materials are well tolerated by the brain and could be used in the fabrication of neuroprosthetic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689766
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  • 3
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of cAMP and cGMP in cells of the rat carotid body following natural and pharmacological stimulation (1991)
    Springer
    Histochemistry and cell biology 96 (1991), S. 523-530 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although the chemoreceptive function of the carotid body has been known for many decades, the cellular mechanisms of sensory transduction in this organ remain obscure. Common elements in the transductive processes of many cells are the cyclic nucleotide second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Studies from our laboratory have revealed stimulus-induced changes in cyclic nucleotide levels in the carotid body as measured by RIA, but such changes in second messenger levels have not been localized to specific cellular elements in the organ. The present immunocytochemical study utilized the avidin-biotin-peroxidase method to investigate the distribution of cAMP and cGMP in the rat carotid body and to assess changes in the intensity of immunostaining following in vitro stimulation by hypoxia, forskolin, sodium nitroprusside, high potassium, and atrial natriuretic peptide. Both cAMP and cGMP immunoreactivity were localized to type I cells of organs maintained in vivo and fixed by perfusion. Organs exposed to 100% O2-equilibrated media in vitro produced low but visible levels of cAMP immunoreactivity in a majority of type I cells; hypoxia (5% O2-equilibrated media) for 10 min moderately increased the level of immunoreactivity; forskolin (10−5 M), or forskolin combined with hypoxia, dramatically increased cAMP levels in virtually all cells. Moderate levels of cGMP immunoreactivity in control carotid bodies in vitro were strikingly reduced by hypoxia; a significant increase in cGMP levels occurred following incubation in high potassium (100 mM), and under these conditions, the decrease in cGMP immunoreactivity with hypoxia was much more pronounced. The synthetic analog of atrial natriuretic peptide, atriopeptin III (10−7 M), greatly elevated cGMP immunoreactivity in the type I cells. On the other hand, sodium nitroprusside (1 mM) elevated cGMP staining mostly in vascular elements of the carotid body in vitro. The data implicate the involvement of cyclic nucleotides in transduction of natural chemosensory stimuli by the type I cells in rat carotid body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267078
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  • 4
    Electronic Resource
    Electronic Resource
    The ultrastructure of astrocytes, oligodendrocytes, and microglia in the optic nerve of urodele amphibians (A. punctatum, T. pyrrhogaster, T. viridescens) (1977)
    Springer
    Journal of neurocytology 6 (1977), S. 269-286 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent ultrastructural studies which indicate a single type of glial cell in the amphibian optic nerve are contradicted by the results of the present investigation demonstrating three types of glial cells in the optic nerve of adult newtsT. viridescens andT. pyrrhogaster, and the neotenous salamanderA. punctatum. Well differentiated astrocytes, oligodendrocytes and microglia are the principal glial constituents with cytological characteristics corresponding to glial elements in the optic nerve of mammals. Immature astrocytes and oligodendrocytes are also present in the nerve indicating continuing production of cells from neuro-ectodermal precursors. Astrocytes constitute approximately 80% of the total. Processes of the large multipolar elements divide axons into bundles and extend to the pial surface to form the glia limitans. A distinct inter-species variability (6–17%) in oligodendrocytes is apparently related to differences in the incidence of myelinated axons. Microglia are the least numerous cellular element constituting only 2–6%. They arise, in part, from monocytic cells near the pial surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01175191
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  • 5
    Electronic Resource
    Electronic Resource
    Ependymal and subependymal cells of the caudato-pallial junction in the lateral ventricle of the neonatal rabbit (1972)
    Springer
    Cell & tissue research 132 (1972), S. 297-322 
    Details
    ISSN: 1432-0878
    Keywords: Neonatal brain (rabbit) ; Ependymal cells ; Subependymal cells ; Lateral ventricle ; Electronmicroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characteristics of a concentration of mitotically active cells near the lateral margin of the lateral ventricle was studied in the neonatal rabbit brain. This area, termed the caudato-pallial area, consists of subependymal cells, neuroblasts, microglial cells and astroblasts bordering a layer of ependymal epithelial cells. The character of the ependymal cells in this area indicates a persistence of embryonic conditions favoring the development of neuroblasts and astroblasts. It is not known what type of cells are produced in the subependymal layer since the primitive subependymal cells have no features which would clearly relate them to nerve or glial cells. Of the 80 subependymal cells which were reconstructed from serial sections none have processes extending beyond the limits of the subependymal layer. They range in form from simple cells devoid of processes to complex cells with several short cellular extensions. The presence of intermediate forms with transitional cytologic features indicates simple and complex cells may represent different stages in the mitotic cycle of a single cell type. No direct evidence was obtained to support the concept that the small ramified microglial cells of the caudato-pallial area or round and amoeboid microglial cells near the corpus callosum arise through mitosis of nearby ependymal or subependymal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450711
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  • 6
    Electronic Resource
    Electronic Resource
    The ultrastructure and source of nerve endings in the carotid body (1974)
    Springer
    Cell & tissue research 154 (1974), S. 303-319 
    Details
    ISSN: 1432-0878
    Keywords: Carotid body (Cat) ; Chemoreceptor ; Nerve endings ; Glossopharyngeal nerve ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of nerve endings in the cat carotid body was analyzed by serial section electron microscopy. In the normal animal, three types of intralobular endings can be recognized. The first type consists of large, calyciform endings which surround glomus cells. The second type includes small calyciform endings which arise from a thin axon and also contact glomus cells. Interstitial enlargements enveloped by sustentacular cells having no direct contact with glomus cells constitute a third type of nerve ending. Intracranial section of the glossopharyngeal nerve caused no change in the number or appearance of intralobular endings, indicating that they are afferent terminals. Stromal axons in the connective tissue of the carotid body may be autonomicfibers as indicated by their degeneration following removal of the superior cervical ganglion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223728
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  • 7
    Electronic Resource
    Electronic Resource
    Early axonal changes following lesions of the dorsal columns in rats (1974)
    Springer
    Cell & tissue research 149 (1974), S. 1-20 
    Details
    ISSN: 1432-0878
    Keywords: Axon sprouts ; Regeneration ; Dorsal column lesion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A graded series of changes occur around lesions to the central nervous system. In the present investigation three zones were distinguished caudal to a lesion of the dorsal columns in the rat, In Zone I near the lesion, necrosis and cellular disintegration are followed by phagocytosis, and the development of a loose connective tissue matrix. Here Schwann cells proliferate and envelope axon sprouts in a similar fashion to those in developing of regenerating peripheral nerve. Zone II includes the proximal segment of nervous tissue containing normal appearing axons in continuity with parent nerve cells. Here an initially severe edematous condition is followed by growth and proliferation of astrocytes. Axon sprouts are present in the transitional Boundary Zone the first day following a lesion. They continue to grow and are most numerous at one week. By two weeks axons have apparently disappeared from many parts of Zone I and degeneration of parent axons and retraction clubs is advanced in Zone II. The reasons for axon involution are not known but do not appear to be related to the development of a glial scar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209047
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  • 8
    Electronic Resource
    Electronic Resource
    Axon regeneration across the site of injury in the optic nerve of the newt Triturus pyrrhogaster (1977)
    Springer
    Cell & tissue research 179 (1977), S. 501-516 
    Details
    ISSN: 1432-0878
    Keywords: Axon regeneration ; Optic nerve ; Triturus pyrrhogaster ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The process by which axons regenerate following a freeze injury to the optic nerve of the newt was analyzed by light and electron microscopy. Freezing destroys cellular constituents in a one millimeter segment of the nerve, leaving intact the basal lamina and the blood supply to the eye. No axons are seen at the site of injury one to seven days post lesion. This contrasts with the persistence of normal-appearing but severed unmyelinated axons within the cranial stump which thus give a false appearance of early regeneration. The first axon sprouts traverse the lesion and enter the cranial stump by ten days. The number of regenerating axons increases rapidly thereafter with no signs of random growth at the site of injury. These axon sprouts tend to be somewhat larger than normal unmyelinated axons and contain dense core vesicles and abnormal organelles similar to those in growing axons in tissue culture. The persisting basal lamina inside the optic sheath appears to provide continuity across the site of injury, to orient axon sprouts, and to favor an orderly process of axon regeneration without neuroma formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219852
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  • 9
    Electronic Resource
    Electronic Resource
    Pericytes and perivascular microglial cells in the basal forebrain of the neonatal rabbit (1975)
    Springer
    Cell & tissue research 158 (1975), S. 517-541 
    Details
    ISSN: 1432-0878
    Keywords: Pericytes and Microglia ; Neonatal rabbit ; Forebrain ; Golgi method ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three types of pericytes outline the vascular bed in Golgi preparations of the newborn rabbit brain. Elongate cells (Type I) are restricted to capillaries, elements resembling smooth muscle cells (Type II) surround vessels of intermediate size, and large flat forms (Type III) cover the surface of arterioles and venules. Electron microscopy shows all types to be located within a well defined perivascular basement membrane. It also reveals the presence of filaments in the cytoplasm of some pericytes resembling the myofilaments of smooth muscle cells. It suggests the possibility that some pericytes are capable of contraction and may participate in regulating blood flow in small vessels. Microglia cells bear no resemblance to pericytes in terms of their shape, distribution or staining characteristics. Microglia cells are located outside the vascular basement membrane (external basal lamina) in the brain parenchyma, and they vary in form according to their location and the character of the surrounding extracellular space. This study does not support the hypothesis that microglia cells arise from pericytes but indicates that they originate either by in situ division or from hematogenous elements that enter the brain by crossing the vessel wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220217
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of millimeter-wave radiation on monolayer cell cultures. II. Scanning and transmission electron microscopy (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 2 (1981), S. 141-150 
    Details
    ISSN: 0197-8462
    Keywords: millimeter-wave radiation ; BHK-21/C13 cells in monolayer culture ; scanning electron microscopy ; transmission electron microscopy ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Both thermal and athermal effects of millimeter-wave radiation on BHK-21/C13 cells were sought using scanning and transmission electron microscopy in conjunction with an in vitro technique that allows direct exposure of monolayer cultures to high average power densities. Culture dishes were irradiated by placing them on the open end of an E- or U-band wave guide. This technique exposes different regions of the cell monolayer lying along the longer axis of the wave guide aperture to varying power densities ranging from zero at each edge to twice the average power density at the center.Cell ultrastructure was unaffected by microwave radiation for 1 hour (41.8 or 74.0 GHz, average power densitites = 320 or 450 mW/cm2, respectively) with or without cooling by rapid recirculation of the culture medium. Temperature in recirculated cultures was held at 37.2 °C, and that in noncooled cultures never exceeded 42 °C during irradiation at either power density. In contrast, cell morphology was affected by microwave exposure whenever irradiation conditions were altered so that the temperature of the monolayer reached or exceeded 44.5 °C. Ultrastructural alterations included breakage of cell processes, progressive detachment of cells from the substrate, increased clumping of heterochromatin in the nuclei, and the appearance of large empty vesicles in the cytoplasm. Such morphological changes resulted from either application of higher average power densities or irradiation at the power densities described above at a higher ambient temperature (〉38.5°C).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250020205
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