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  • 1
    Electronic Resource
    Electronic Resource
    Electron Microscope Observations of Neurosecretory Elements in the Neurointermediate Lobe in Skates (1965)
    [s.l.] : Nature Publishing Group
    Nature 208 (1965), S. 94-95 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] With the light microscope, it was found that bundles of the neurosecretory fibres were between the strands of the epithelial glandular cells of the intermediate lobe and elements of connective tissue, and vessels were not found in these spaces. The terminal branches of the neurosecretory fibres are ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/208094a0
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative localization of corticotropin and corticotropin releasing factor-like peptides in the brain and hypophysis of a primitive vertebrate, the sturgeonAcipenser ruthenus L. (1992)
    Springer
    Journal of neurocytology 21 (1992), S. 885-896 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sturgeon is a primitive actinopterigian fish that, unlike modern teleosts, possess a portal vascular system that connects a true median eminence with the anterior pituitary as in mammals. The occurrence and localization of corticotropin and corticotropin releasing factor-like immunoreactivities were examined in the brain of the sturgeon (Acipenser ruthenus L.) by immunocytochemistry with antisera raised against synthetic non-conjugated human corticotropin, and rat/human corticotropin releasing factor. In the hypothalamus, corticotropin-immunoreactive parvicellular perikarya were found in the infundibular nucleus and in dendritic projections to the infundibular recess. In addition, ependymofugal corticotropin-immunoreactive fibres were found to terminate in the ventral hypothalamus. Corticotropin releasing factor-immunoreactive neurons were found in the rostral portion of the ventral hypothalamus (tuberal nucleus), and in the vicinity of the rostral aspect of the lateral recess. These cells projected to the dorsal hypothalamus, the ventral hypothalmus, the median eminence, the anterior and posterior telencephalon, the tegmentum mesencephali, and the pars nervosa of the pituitary. An affinitypurified UI antiserum failed to stain the sturgeon hypothalamus. Corticotrophs in the rostral pars distalis of the pituitary were also corticotropin-immunoreactive. In the neurointermediate lobe, only about 50% of cells of the pars intermedia appeared to be corticotropin-positive, the rest appeared unstained. These results suggest that the presence of corticotropin-like and corticotropin releasing factor-like peptides in the brain is a relatively early event in vertebrate evolution, already occurring in Chondrostean/Actinopterigian fishes, as exemplified byA. ruthenus. The close spatial relationship between corticotropin releasing factor immunoreactivity and corticotropin immunoreactivity in the ventral hypothalamus ofA. ruthenus supports a possible interaction between the two systems in that area of the sturgeon brain. The pars intermedia might be an important site for corticotropin synthesis, even though the possibility cannot be excluded that the antiserum was recognizing the proopiomelanocortin molecule. The occurrence of corticotropin releasing factor immunoreactivity in the region of median eminence/pars intermedia of the sturgeon suggests that the sturgeon corticotropin releasing factor might regulate the adenohypophyseal release of proopiomelanocortin products in the same manner as in other vertebrates. The presence of extrahypothalamic corticotropin releasing factor-immunoreactive projections suggests further neuromolulatory functions for this peptide inA. ruthenus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01191685
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  • 3
    Electronic Resource
    Electronic Resource
    The hypothalamo-hypophysial system of hypophysectomized rats (1974)
    Springer
    Cell & tissue research 155 (1974), S. 541-554 
    Details
    ISSN: 1432-0878
    Keywords: Hypophysectomized rats ; Reorganized stalk ; Ultrastructure ; Salt load
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The reorganized stalk of hypophysectomized rats, either “intact” or subjected to a 6-day salt load, has been studied by light and electron microscopy. PAF-positive neurosecretory material is seen mainly in the periphery of the reorganized stalk, usually in 2–5 μ nerve swellings of animals operated two months before. Nerve swellings make contact with a dense capillary network. Three types of nerve fibres and their swellings are distinguished according to the size of elementary granules. Peptidergic A1 and A2 types contain granules with a maximum diameter of 170 and 130 nm respectively; monoaminergic B type fibres have granules of 100 nm in diameter. A1 type axonal swellings are the most numerous and can be tentatively divided into four subtypes according to their ultrastructure and relationships with capillaries and pituicytes. Swellings of types b and c, making direct contact with capillaries or pituicyte perikarya, usually contain few granules and numerous synaptic vesicles arranged frequently in clusters in the “active” zones. It is assumed that they are especially active in the release of peptide neurohormones. It is also hypothesized that in the hypophysectomized rats peptide neurohormones are released not only directly into the pericapillary space but also into the intercellular cleft, especially at sites of neuron-pituicyte junctions. Nerve swellings of type a, separated from the pericapillary space by thin pituicyte processes, usually contain numerous neurosecretory granules. It is suggested that vascular “end-feet” of pituicytes may somehow reduce neurohormone release. The depletion of PAF-positive material as well as the decreased granule content even after a salt load of only 1 per cent shows that the reorganized stalk is functional as a neurohaemal organ, but has a diminished hormone reserve. This, together with a primitive cytomyeloangioarchitecture speaks for morphological and functional imperfection of the reorganized stalk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227014
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  • 4
    Electronic Resource
    Electronic Resource
    On degeneration of peptidergic neurosecretory fibres in the albino rat (1975)
    Springer
    Cell & tissue research 160 (1975), S. 113-123 
    Details
    ISSN: 1432-0878
    Keywords: Posterior pituitary ; Rats ; Degeneration ; Salt load ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three types of degenerating peptidergic neurosecretory fibres have been found in the posterior pituitary of chronically dehydrated albino rats. “Dark” neurosecretory fibres and their swellings contain neurosecretory granules, neurotubules, shrunken mitochondria and diffusely distributed fine dense material. Some swellings are filled with synaptic vesicles and/or conglomerations of dense membranes. The transitional forms exist between these fibres and extracellular accumulations of electron dense material. Synaptic vesicles, single neurosecretory granules, lipid-like droplets and lamellar bodies occur in the latter. Some neurosecretory fibres and swellings have numerous polymorphous inclusions arising due to degradation of secretory inclusions and organelles, mitochondria and neurotubules in particular. “Dark” neurosecretory elements and those with numerous polymorphous inclusions are enveloped by pituicyte cytoplasm. Sometimes the plasma membranes both of the pituicytes and neurosecretory fibres are destroyed or transformed into a multi-membrane complex. It is assumed that pituicytes may phagocytize degenerating neurosecretory elements. Neurosecretory fibres with a locally dissolved neuroplasm and/or large lucent vacuoles seem to be due to axonal degeneration by the “light” type. These neurosecretory elements, the largest of them in particular, may transform into large cavities bordered by a membrane and containing flake-like material and single-membrane vacuoles. Degeneration of neurosecretory elements seems to occur mainly due to hyperfunction of the hypothalamo-hypophysial neurosecretory system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219845
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  • 5
    Electronic Resource
    Electronic Resource
    The hypothalamo-hypophysial system in acipenseridae (1972)
    Springer
    Cell & tissue research 128 (1972), S. 470-481 
    Details
    ISSN: 1432-0878
    Keywords: Hypophysis ; Neuro-intermediate complex ; Acipenseridae ; Adrenergic fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of adrenergic and peptidergic (“Gomori-positive”) structures of the hypophysial neuro-intermediate complex in Acipenseridae has been studied by means of light, fluorescence, and electron microscopy. Adrenergic fibres (B-fibres) and their terminals have been detected in the neurohypophysis of these fishes. The terminal swellings of B-fibres as well as the terminals of the neurosecretory peptidergic fibres (A1 and A2) make contact with the basement membrane of the connective tissue layer separating the neurohypophysis from the intermediate lobe. Capillaries are situated within this layer and, therefore, the main part of the fibre terminals is in contact with the pericapillary space. The release of catecholamines from the adrenergic terminals into the capillaries connected with the general circulation is supposed. The diffusion of catecholamines through the connective tissue layer into the parenchyma of the intermediate lobe is also suggested. Hence, the glandular activity of the intermediate lobe seems to be under the dual control of adrenergic and peptidergic elements of the hypothalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306983
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  • 6
    Electronic Resource
    Electronic Resource
    The hypothalamo-hypophysial system in Acipenseridae (1976)
    Springer
    Cell & tissue research 170 (1976), S. 129-144 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; Acipenseridae ; Neurovascular link ; Neuroglial elements ; Light, fluorescence and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proximal neurosecretory contact region (PCR) of Acipenseridae, a homologue of the tetrapod median eminence, has been studied by light, fluorescence and electron microscopy. It occupies the rostral and chiefly the ventral surfaces of the hypothalamic tuber cinereum. PAF-positive fibres occur in the zone of the preoptico-hypophysial tract but their terminal enlargements are concentrated mainly in the external zone. They make contact with the primary portal capillaries situated in the pia mater. Monoaminergic fibres and terminals with an intense green fluorescence are localized in the same regions. The fibres of some bipolar monoaminergic neurons of the PCR make contact both with the third ventricle and the primary portal capillaries. Three types of granule-containing neurosecretory fibres and terminals have been recognized in the PCR. Fibres of types A1 (d=120–300 nm) and A2 (d=100–170 nm) are peptidergic PAF-positive, although some fibres, including some of type A1; belong possibly to PAF-negative type. Monoaminergic type B fibres have granules 80–100 nm in diameter. Neurosecretory terminals and vascular “endfeet” of tanycytes make contact with the 70 nm thick outer basement membrane of the primary portal capillaries. Several laminae of thin horizontally oriented tanycyte processes form a boundary between the external zone and the preoptico-hypophysial tract. Few neuroglial cells with pale cytoplasm, numerous lysosomes and lipofuscin granules are seen in this region. It is hypothesized that, as in other vertebrates, both peptide hypophysiotropic neurohormones and monoamines are discharged from the PCR into the portal circulation and affect the activity of the glandular cells of the pars distalis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220115
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  • 7
    Electronic Resource
    Electronic Resource
    The hypothalamo-hypophysial system of the lamprey, Lampetra fluviatilis L. (1974)
    Springer
    Cell & tissue research 150 (1974), S. 505-519 
    Details
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Lamprey ; Neurovascular link ; Tanycytes ; Light ; Fluorescence and Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three zones are observed in the neurohypophysis (Nh) of adult Lampetra fluviatilis: 1) an internal, containing tanycyte perikarya, 2) a middle and 3) an external zone. Gomori-positive fibres and their enlargements occur in the middle and especially in the external zone. In the latter they have a palisade-like arrangement on the connective tissue layer (CTL) separating the Nh and the intermediate lobe. Wide sinusoid capillaries are situated in the CTL. Where capillaries are absent, the latter is rather thin. With Falck's technique a mainly diffuse intense green fluorescence is observed in the middle and especially in the external zones. Fluorescent droplets and fibres with varicose swellings are rare. Two types of tanycyte—“light” and “dark”,—are distinguished. Few funnel-shaped protrusions of the recessus infundibuli lined with tanycytes penetrate deeply in the Nh. Pituicytes are rare. Peptidergic A1 and A2 fibres and their terminals contain granules of 160–340 nm and 120–220 nm in diameter respectively. Monoaminergic B type fibres have granules of 80–100 nm in diameter. Percentage of the A1 fibres is the lowest. Nerve terminals and tanycyte vascular endfeet make contact with the unusually thick (up to 300 nm) outer basement membrane. The latter is about 1 μ thick in sites where it invaginates deeply into the Nh. Single short fragments of the inner basement membrane are seen. Sometimes peptidergic A1 and A2 nerve terminals are separated from the recessus infundibuli only by a thin layer of tanycyte cytoplasm. Peptide neurohormones are probably released in cerebro-spinal fluid in these sites. The possibility of peptide neurohormones and monoamines to be discharged into the common circulation and their diffusion through the CTL into the intermediate lobe is supposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225974
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