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  • 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
    Ependymal specializations (1970)
    Springer
    Cell & tissue research 111 (1970), S. 15-31 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Toads ; Apical secretion ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ependymal cells of the toad subcommissural organ produce pale and dense secretory granules. Both types of granules are mainly concentrated in the apical cytoplasm and in the perinuclear region. Pale and dense granules are synthesized by and packed in the rough endoplasmic reticulum, bypassing the step of the Golgi apparatus. The apical cytoplasm of some subcommissural ependymal cells protrudes into the ventricle. All the cells project a few cilia and numerous slender, long microvilli into the ventricular lumen. Contacting the cilia and the microvilli there is a filamentous material identical to that observed in the fibre of Reissner at the aqueduct of Sylvius. In addition to filaments, the fibre of Reissner contains vacuolar formations. The fibre is surrounded by numerous ependymal cilia, some of which are embedded in the filamentous material of the fibre. The presence of numerous microvilli projected into the ventricle and the large number of vesicles scattered in the supranuclear cytoplasm seem to indicate that the subcommissural organ may have absorption functions. The fact that the intercellular space of the ependymal layer of the subcommissural organ is not separated from the ventricular lumen by tight junctions but by zonulae adhaerentes could indicate that the cerebrospinal fluid penetrates these intercellular spaces bathing all sides of the ependymal cells. The presence in the ependymal cells of vesicles opening into the intercellular space would be in agreement with the latter possibility. There are some ultrastructural differences between the ependymal cells of the cephalic end of the subcommissural organ and those of the caudal end. A critical analysis of Reissner's fibre formation is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342098
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  • 3
    Electronic Resource
    Electronic Resource
    The infundibular organ of the lancelet (Branchiostoma lanceolatum, Acrania): an immunocytochemical study (1994)
    Springer
    Cell & tissue research 277 (1994), S. 107-114 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Reissner's fiber – Infundibular organ – Immunocytochemistry – Lectin binding – Flexural organ – Amphioxus, Branchiostoma lanceolatum (Acrania)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Reissner's fibers are secretions produced by different ependymal areas of the chordate brain, viz., in adult vertebrates, by the dorsal subcommissural organ, and in all stages of cephalochordates (Branchiostoma lancelets), by the ventral infundibular organ. Fibers produced by these different organs are seemingly identical and the two fiber sources also share some immunocytochemical and lectin-binding properties. The secretions in these two glands are, however, not identical; the infundibular organ cells are strongly reactive with antibodies against vertebrate Reissner's fibers, but they do not react with antibodies raised against the source of the vertebrate fibers, viz., the subcommissural organ. The results support the possibility that, in adult vertebrates, the Reissner's fibers are composed of material not only from the subcommissural organ, but also from another, not yet identified, source that is identical or equivalent to the infundibular organ of the lancelet. There are indications that the infundibular organ is immunocytochemically closely akin to some secretory cells in the vertebrate embryonic brain and also to those that produce the juvenile vertebrate Reissner's fibers, viz., secretory cells in the flexural organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303086
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of adenohypophysectomy on the hypothalamic-hypophysial neurosecretory system and the adrenal gland of the toad Bufo arenarum Hensel (1967)
    Springer
    Cell & tissue research 80 (1967), S. 93-107 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of adenohypophysectomy were studied on the hypothalamichypophysial neurosecretory system and the adrenal glands of Bufo arenarum Hensel. An increase in vascularization of the pars intermedia was found and the neurosecretory material (NSM) in the glandular region of the median eminence disappeared. Its reappearance later was accompanied by hypertrophy of the pars intermedia; differentiated chromophil cells appeared in the pars intermedia around the vessels and, at the same time, the adrenal reverted to normal. These findings are interpreted as hypertrophy and differentiation of the pars intermedia with replacement, at least partly, of the functions of the pars distalis. The probable mechanism of differentiation and the functions of chromophil cells of the pars intermedia are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331479
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  • 5
    Electronic Resource
    Electronic Resource
    The infundibular organ of the lancelet (Branchiostoma lanceolatum, Acrania): an immunocytochemical study (1994)
    Springer
    Cell & tissue research 277 (1994), S. 107-114 
    Details
    ISSN: 1432-0878
    Keywords: Reissner's fiber ; Infundibular organ ; Immunocytochemistry ; Lectin binding ; Flexural organ ; Amphioxus, Branchiostoma lanceolatum (Acrania)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Reissner's fibers are secretions produced by different ependymal areas of the chordate brain, viz., in adult vertebrates, by the dorsal subcommissural organ, and in all stages of cephalochordates (Branchiostoma lancelets), by the ventral infundibular organ. Fibers produced by these different organs are seemingly identical and the two fiber sources also share some immunocytochemical and lectin-binding properties. The secretions in these two glands are, however, not identical; the infundibular organ cells are strongly reactive with antibodies against vertebrate Reissner's fibers, but they do not react with antibodies raised against the source of the vertebrate fibers, viz., the subcommissural organ. The results support the possibility that, in adult vertebrates, the Reissner's fibers are composed of material not only from the subcommissural organ, but also from another, not yet identified, source that is identical or equivalent to the infundibular organ of the lancelet. There are indications that the infundibular organ is immunocytochemically closely akin to some secretory cells in the vertebrate embryonic brain and also to those that produce the juvenile vertebrate Reissner's fibers, viz., secretory cells in the flexural organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303086
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  • 6
    Electronic Resource
    Electronic Resource
    Ependymal specializations (1970)
    Springer
    Cell & tissue research 111 (1970), S. 32-50 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Toads ; Basal secretion ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basal processes of the subcommissural ependymal cells contain filaments, microtubules, mitochondria and numerous pale and dense secretory granules. Both types of secretory granules are more numerous in the dilated portions of the ependymal processes. It is postulated that the periodical dilatations filled with secretory granules are responsible for the “rosary” appearance of the ependymal processes when stained with aldehyde fuchsin or chrome alum-hematoxylin. The ependymal processes of some ependymal subcommissural cells end on the external limiting membrane which covers the brain surface. The ependymal endings contain, among other structures, secretory granules and cisternae of the rough endoplasmic reticulum; this suggests that the secretory material may be locally synthetized. The presence in the subarachnoid space, close to the ependymal endings, of a particular type of blood capillaries supports the possibility of a vascular release of the secretory material present in the ependymal endings. The processes of other subcommissural ependymal cells end on blood capillaries localized in the subependymal neuropile. These capillaries have a distinctive perivascular space, where the external perivascular basement membrane is covered by a continuous “cuff” formed by ependymal endings containing secretory granules. Here again, the vascular release of the ependymal secretion seems very likely. Lastly, a third group of ependymal processes end on cavities lined by a basement membrane. It is thought that these cavities are “prolongations” of the perivascular space of the subependymal capillaries; this would contribute to establish numerous ependymo-vascular connections despite the scarce number of blood vessels. Some evidence supporting the possibility that the ependymal cells of the subcommissural organ are innervated is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342099
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Comparative immunocytochemical study of the subcommissural organ (1984)
    Springer
    Cell & tissue research 237 (1984), S. 427-441 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Reissner's fiber ; Ependyma ; Secretory process ; Comparative analysis ; Immunocytochemistry ; Vertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organs (SCO) of 76 specimens belonging to 25 vertebrate species (amphibians, reptiles, birds, mammals) were studied by use of the immunoperoxidase procedure. The primary antiserum was obtained by immunizing rabbits with bovine Reissner's fiber (RF) extracted in a medium containing EDTA, DTT and urea. Antiserum against an aqueous extract of RF was also produced. The presence of immunoreactive material in cell processes and endings was regarded as an indication of a possible route of passage. Special attention was paid to the relative development of the ventricular, leptomeningeal and vascular pathways established by immunoreactive structures. The SCO of submammalian species is characterized by (i) a conspicuous leptomeningeal connection established by ependymal cells, (ii) scarce or missing hypendymal cells, and (iii) a population of ependymal cells establishing close spatial contacts with blood vessels. The SCO of most mammalian species displays the following features: (i) ependymal cells lacking immunoreactive long basal processes, (ii) hypendymal secretory cells occurring either in a scattered arrangement or forming clusters, (iii) an occasional leptomeningeal connection provided by hypendymal cells, and (iv) in certain species numerous contacts of secretory cells with blood vessels. In the hedgehog immunoreactive material was missing in the ependymal formation of the SCO, but present in hypendymal cells and in the choroid plexuses. The SCO of several species of New-and Old-World monkeys displayed immunoreactive material, whereas that of anthropoid apes (chimpanzee, orangutan) and man was completely negative with the antisera used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228427
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  • 9
    Electronic Resource
    Electronic Resource
    Spatial and structural interrelationships between secretory cells of the subcommissural organ and blood vessels (1984)
    Springer
    Cell & tissue research 237 (1984), S. 443-449 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Ependyma ; Comparative aspects ; Immunocytochemistry ; Secretory process ; Blood vessels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In 76 specimens (amphibians, reptilians, mammals) belonging to 25 different vertebrate species, the region of the subcommissural organ (SCO) was investigated with the use of a primary antiserum raised against an extract of bovine Reissner's fiber+the immunoperoxidase procedure according to Sternberger et al. (1970). In the SCO of a toad (Bufo arenarum) and several species of reptiles (lacertilians, ophidians, crocodilians), the ependymal cells were the only type of secretory cell displaying vascular contacts, whereas in mammals ependymal and hypendymal cells established intimate spatial contacts with blood vessels. In Bufo arenarum, but especially in the reptilian species examined, the ependymo-vascular relationship was exerted by a population of ependymal cells having a rather constant location within the SCO and projecting to capillaries that showed a remarkably constant pattern of anatomical distribution. In the SCO of mammals the modality and degree of the structural relationships between secretory cells and blood vessels varied greatly from species to species. In the SCO of the armadillo and dog the secretory tissue was organized as a thick, highly vascularized layer with most of the cells oriented toward the capillaries. A rather opposite situation was found in the SCO of New-and Old-World monkeys, where vascular contacts were restricted to a few ependymal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228428
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  • 10
    Electronic Resource
    Electronic Resource
    Immunocytochemical and ultrastructural evidence for a neurophysinergic innervation of the subcommissural organ of the snake Natrix maura (1987)
    Springer
    Cell & tissue research 248 (1987), S. 473-478 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Innervation ; Neu rophysins ; Mesotocin ; Immunocytochemistry ; Ultrastructure ; Snake, Natrix maura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organ (SCO) of the snake Natrix maura was studied by use of the immunoperoxidase procedure. Primary antisera against bovine neurophysins (Nps I + II, OXY-Np), oxytocin (OXY), mesotocin (MST), arginine-vasotocin (AVT), somatostatin (SOM), β-endorphin (END) and bovine Reissner's fiber were used. A conventional ultrastructural study, with special emphasis on the nerve fibers present in the SCO, was also performed. Nerve fibers containing immunoreactive OXY-Np and MST were seen to reach the SCO. The staining of adjacent sections with the anti-Reissner's fiber serum showed that the OXY-Np- and MST-immunoreactive fibers were distributed among the cell bodies and processes of the ependymal secretory cells. No fibers containing immunoreactive OXY, AVT, SOM or END were found in the SCO. The ultrastructural analysis revealed in the SCO the presence of nerve fibers filled with electron-dense granules, 170–210 nm in diameter. Although a direct apposition between these fibers and the SCO cells was frequently seen, no synaptic differentiations were identified. Structures identical to the Herring bodies (found in the neurohypophysis) were seen in the SCO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218215
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