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  • Articles: DFG German National Licenses  (27)
  • 1
    Electronic Resource
    Electronic Resource
    The metencephalic floor plate of chick embryos expresses two secretory glycoproteins homologous with the two glycoproteins secreted by the subcommissural organ (2000)
    Springer
    Histochemistry and cell biology 113 (2000), S. 415-426 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nature and the function of the compounds secreted by the floor plate (FP) of the metencephalon are little known. The FP cells of the hindbrain react with antibodies (AFRU) against the glycoproteins secreted by the subcommissural organ (SCO). One of the these proteins, RF-Gly I, is a 540-kDa core glycosylated protein. The aims of the present investigation were to identify by immunoblot the AFRU-immunoreactive compound secreted by the FP of chick embryos, to establish temporal and regional patterns of this secretory activity, and to obtain information about the fate of these compounds. It was established that the SCO and FP of chick embryos secrete two AFRU-immunoreactive compounds of 540 and 230 kDa. The two compounds secreted by the FP have been designated as FP-Gly I and FP-Gly II. The expression of these proteins was circumscribed to the metencephalic FP, and occurred from HH 29 to HH 36. Within the FP cells, FP-Gly I and FP-Gly II were confined to the supranuclear and apical regions, which under the electron microscope displayed numerous cisternae of the rough endoplasmic reticulum and granules. Aggregates of AFRU-immunoreactive material appeared on the free surface of the FP. The possibility that FP-Gly I and FP-Gly II are released into the ventricle to reach distant targets is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180000136
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  • 2
    Electronic Resource
    Electronic Resource
    Intercellular channels in the pars tuberalis of the rat hypophysis and their relationship to the subarachnoid space (1981)
    Springer
    Cell & tissue research 218 (1981), S. 345-354 
    Details
    ISSN: 1432-0878
    Keywords: Hypophysis ; Pars tuberalis ; Intercellular channels ; Subarachnoid space ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A system of intercellular channels is described in the pars tuberalis (PT) of the female rat. These spaces are lined by all types of cells found in the PT and are not sealed off by tight junctions. Ventrally and dorsally, the intercellular spaces open toward the basement membranes separating the PT from (i) the subarachnoid space, and (ii) the perivascular space of the portal capillaries, respectively. These intercellular channels differ from the follicles, which are also found in the PT, being lined by a particular type of cell. In a second group of female rats an epoxy mixture was injected into the third ventricle; 10 min thereafter horseradish peroxidase was infused into the cisterna magna. After processing the brain for the demonstration of exogenous peroxidase, it was found that the tracer had reached the subarachnoid space adjacent to the hypothalamus and entered into all ventricular cavities with the exception of the infundibular recess. Under these experimental conditions it was found that the tracer fills all intercellular channels of the PT, thus indicating that there is no barrier between the subarachnoid space and the PT. It is suggested that the subarachnoid space should be regarded as a probable route for the transport of trophic factor(s) and/or secretory product(s) of the PT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210349
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  • 3
    Electronic Resource
    Electronic Resource
    Reissner's fiber, massa caudalis and ampulla caudalis in the spinal cord of lamprey larvae (Geotria australis) (1987)
    Springer
    Cell & tissue research 247 (1987), S. 359-366 
    Details
    ISSN: 1432-0878
    Keywords: Reissner's fiber ; Massa caudalis ; Subcommissural organ ; Spinal cord ; Central canal ; Immunocytochemistry ; Lectin histochemistry ; Lamprey ; Geotria australis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organ (SCO), Reissner's fiber (RF) and its massa caudalis of lamprey larvae (Geotria australis) were investigated immunocytochemically by use of an antiserum raised against bovine RF as primary antibody. The affinities of RF and massa caudalis for Ricinus communis agglutinin I (RCA) with and without previous acid hydrolysis, concanavalin A (Con A), wheat-germ agglutinin (WGA), aldehyde fuchsin, and PAS reaction were also studied. SCO and massa caudalis were strongly immunoreactive, whereas RF proper was distinctly negative. RF did not react with Con A and RCA. Only the periphery of RF was WGA-positive. RCA showed affinity for RF only after acid hydrolysis. RF was homogeneously stained by the aldehyde-fuchsin and PAS-methods. At variance with RF proper, the periphery of the massa caudalis reacted with RCA without previous acid hydrolysis, but its core was WGA-positive and reacted with RCA only after hydrolysis. It is suggested that (i) RF has a coat of glycoproteins containing sialic acid as terminal residue, whereas the massa caudalis possesses a coat with galactose as terminal residue; (ii) in RF proper and the massa caudalis the spatial arrangement of glycoproteins might be different. Routine transmission electron-microscopic observations indicate that in larvae of Geotria australis an open communication exists between the ampulla caudalis and blood capillaries via large cavities or lacunae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218317
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural immunocytochemical study of the massa caudalis of the subcommissural organ-Reissner's fiber complex in lamprey larvae (Geotria australis): Evidence for a terminal vascular route of secretory material (1987)
    Springer
    Cell & tissue research 247 (1987), S. 367-376 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Reissner's fiber ; Massa caudalis ; Vasculature ; Ultrastructural immunocytochemistry ; Lamprey ; Geotria australis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The massa caudalis of the subcommissural organ-Reissner's fiber complex of lamprey larvae (Geotria australis) was studied immunocytochemically at the ultrastructural level by use of the immunoperoxidase-silver methenamine procedure. An antiserum raised against bovine Reissner's fiber was utilized as primary antibody. The caudalmost portion of the central canal and its ampulla caudalis communicate, via wide intercellular spaces in their dorsal wall, with large cavities or lacunae. In addition, distinct openings in the dorsal wall of the ampulla establish an open communication between the latter and the lacunae. The lacunae are lined by slender processes of cells of unknown nature. No junctional complexes can be observed between these cells, which lack a basal lamina. The lacunae communicate with structures resembling blood capillaries, however, they are devoid of a basal lamina. These peculiar vessels, in turn, are in direct communication with characteristic blood capillaries. Reissner's fiber (RF) and its massa caudalis are strongly immunoreactive with the antiserum used. The wide intercellular spaces in the dorsal wall of the central canal and the ampulla, as well as the lumina of the (i) lacunae, (ii) modified vessels and (iii) blood capillaries are filled with a flocculent, strongly immunoreactive material. No immunoreactive material was found outside these structures. Thus, the blood capillaries appear to represent the only final target of RF-material arriving at the ampulla caudalis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218318
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  • 5
    Electronic Resource
    Electronic Resource
    Light and electron-microscopic immunocytochemistry and lectin histochemistry of the subcommissural organ: Evidence for processing of the secretory material (1986)
    Springer
    Cell & tissue research 243 (1986), S. 545-559 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Glycoproteins ; Secretory process ; Immunocytochemistry ; Lectin histochemistry ; Rat ; Vertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organ (SCO) of the rat was investigated by use of histochemical and immunocytochemical methods at the light and electron-microscopic levels. Consecutive thin methacrylate sections were stained with the pseudoisocyanin (Psi), immunoperoxidase (IMC; employing an antiserum against Reissner's fiber, AFRU), periodic acid-Schiff (PAS) and periodic acid-silver methenamine (SM) techniques, and reacted with six types of lectins. Psi, SM, concanavalin A (Con A) and IMC were also used for double and triple sequential staining of the same section. Increasing dilutions of AFRU (from 1∶1000 to 1∶200 000) were used for immunostaining of serial paraffin sections. In addition, ultrastructural localization of (i) Con A-binding sites and (ii) immunoreactive secretory material was performed. Some of these procedures were also applied to the ophidian and canine SCO. Con A-positive, Psi-positive and immunoreactive materials coexisted within the same cisternae of the rough endoplasmic reticulum. The Golgi apparatus lacked Con A-positive and immunoreactive substances. Apical secretory granules and secreted material lying on the surface of the SCO showed (i) the highest affinity for AFRU, but were (ii) Con A-negative, and (iii) wheat-germ agglutinin-, PAS and SM-positive. Reissner's fiber displayed a low affinity for AFRU. It is suggested that the SCO secretes N-linked glycoproteins, the carbohydrate and protein moeities of which undergo (i) a maturation process before being released, and (ii) some kind of modification(s) after their release into the ventricle. The perivascular secretory cells of the dog SCO might secrete a material different from that secreted by the ependymal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218061
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  • 6
    Electronic Resource
    Electronic Resource
    Control of the pars intermedia of the lizard, Anolis carolinensis (1979)
    Springer
    Cell & tissue research 198 (1979), S. 411-426 
    Details
    ISSN: 1432-0878
    Keywords: Intermediate lobe ; Hypophysis ; Ultrastructure ; Colour change ; Control mechanisms ; Anolis carolinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the intermediate lobe of the hypophysis was studied in Anolis carolinensis with the use of a threefold aldehyde fixative. Lizards with a brown skin were selected. The possibility of two types of secretory cells is discussed; neither cell type is innervated. Type I cells are rarely found and contain dense granules approximately 0.3 μm in diameter; Type II cells vary widely in secretory activity. Most of the Type II cells contain a large number of dense secretory granules (up to about 1.3 μm in diameter) almost filling the cytoplasm. Rough endoplasmic reticulum (RER), Golgi apparatus and mitochondria are poorly developed. Only some of these cells show signs suggesting a high secretory activity, namely a well developed RER, Golgi apparatus and numerous mitochondria. In these cells the RER sometimes forms large intracisternal droplets (up to 7 μm in diameter). Two of the animals exhibited a more uniform, high secretory activity. Large (about 2 μm in diameter), pale vacuoles, probably of extracellular character, were found mostly in the vicinity of the perivascular septum. Their role in the release of MSH is discussed. The present data, which are discussed with reference to earlier findings (Forbes, 1972), form the morphological basis for an experimental study on regulation of MSH release (Larsson et al., 1979).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234186
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  • 7
    Electronic Resource
    Electronic Resource
    Control of the pars intermedia of the lizard, Anolis carolinensis (1979)
    Springer
    Cell & tissue research 199 (1979), S. 1-23 
    Details
    ISSN: 1432-0878
    Keywords: Neuro-intermediate lobe ; Hypophysis ; Disconnection ; Ultrastructure ; Colour change ; Control mechanisms ; Anolis carolinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological changes in the disconnected neuro-intermediate lobe were studied in the lizard, Anolis carolinensis from the 2nd to the 14th post-operative day using a threefold aldehyde fixative (Rodríguez, 1969). Two phases of colour change capacity were exhibited: Phase I started immediately after the transection, lasted for 6 days (mean) and was characterised by an excessive MSH release (brown skin). This phase proceeded gradually into Phase II, designated by an interruption of the MSH release (green skin). The degenerative processes and final elimination of neurons in the disconnected neural lobe propagate in a rostro-caudal direction from the transected area. The aminergic fibres (Type II) disappear within 2 days postoperatively, whereas the degeneration continues for more than 10 days in the peptidergic fibres (Type III, IV and V). The glia cells (ependyma and pituicytes) serve as very active macrophages, engulfing fragments of axons already affected by autolysis and transferring them into glial lysosomes. No apparent morphological changes occur in the shift from Phase I to II. The great majority of the secretory cells of the intermediate lobe are not affected by degenerative processes and appear to be markedly activated by the stalk transection. They exhibit numerous mitochondria, well-developed Golgi complexes forming numerous Golgi vesicles and extensive parallel cisternae of the rough endoplasmic reticulum, sometimes forming large intracisternal droplets (7 μm in diameter). Numerous pale vacuoles are seen, especially toward the intact capillaries, suggesting their coupling to the MSH release by extension of the active membrane area toward the perivascular septum. The number of these vacuoles is very markedly reduced in Phase II (no release), whereas the formation of new granules seems to proceed in early stages. The interruption of the MSH release implies a successive refilling of gradually growing secretory granules and a concomitant reduction in the development of the synthetic apparatus. Mechanisms probably involved in the control of the synthesis and release of MSH are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237724
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  • 8
    Electronic Resource
    Electronic Resource
    Differences between median eminence and neural lobe in amphibians (1966)
    Springer
    Cell & tissue research 74 (1966), S. 308-316 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurohypophysis of the toad Bufo arenarum Hensel can be subdivided into two well defined zones: the median eminence and the neural lobe. In its turn, the median eminence consists of two zones: a neural subependymal one, containing the axons of the hypothalamic-neurohypophysial tract; and a glandular one, made up of the capillaries of the primary plexus of the portal hypophysial system and of neurosecretory axons. Different staining techniques and certain experimental procedures (inanition, dehydration and adenohypophysectomy) showed that there are differences between the neurosecretory material of the neural lobe, which is a place of hormone liberation into the systematic circulation, and the neurosecretory material of the median eminence, which is the site of release of adenohypophysis-stimulating substances into the portal vessels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401259
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  • 9
    Electronic Resource
    Electronic Resource
    Vascularization of the hypophysial region of the normal and adenohypophysectomized toad (1967)
    Springer
    Cell & tissue research 83 (1967), S. 207-218 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The study of standarized sections of the hypophysial regions, and in vivo observations showed the presence of communicating vessels between the capillary network of the median eminence and the large capillaries of the neurointermediate junction. Moreover, direct branches from the hypophysial artery are described which give off branches, at the level of the neural stalk, to the median eminence and to the large capillaries of the neurointermediate junction. A second portal system similar to the one described by Cruz has been observed. Its primary plexus originates in several encephalic regions, and its secondary plexus is distributed through the neural lobe and thence to the pars intermedia. The course of flow in this system is a descending one. The arterial contribution to this system appears to arise from branches from the basilar and retroinfundibular arteries. — There are small venous-type vessels between the large capillaries of the neurointermediate junction and the posterodorsal region of the pars distalis. — After adenohypophysectomy, the blood which normally goes towards the pars distalis, flows towards the pars intermedia, following the path of the communicating vessels between the median eminence and the pars intermedia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00362402
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  • 10
    Electronic Resource
    Electronic Resource
    Light and electron microscopy of granules in the toad choroid plexus (1967)
    Springer
    Cell & tissue research 82 (1967), S. 362-375 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two types of granules can be distinguished in the toad choroid plexus under the light microscope: pigment granules, mainly localized in the cells that line the free ends of the choroidal villi, and Gomori-positive granules, present in most epithelial cells. The ultrastructural analysis of the choroid plexus reveals three types of granules: multivesicular bodies (MVB), multigranulous bodies (MGB) and dense bodies (DB), and intermediate stages between the last two bodies. The pigment granules seen under the light microscope probably correspond to the DB of the electron micrographs, and the Gomori-positive granules to the MGB. The probable role of these bodies is discussed and so is the significance of the glycogen present in the choroidal cells, their processes and endothelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323860
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