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  • 1
    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
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  • 2
    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
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  • 3
    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
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  • 4
    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
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  • 5
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Neurophysins ; Vasotocin ; Mesotocin ; Supraoptic nucleus ; Paraventricular nucleus ; Natrix maura (Serpentes) ; Mauremys caspica (Chelonia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake Natrix maura and the turtle Mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. Arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. The same cells appeared to be stained by the anti-oxytocin-neurophysin and anti-mesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina terminalis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunore-active fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.
    Type of Medium: Electronic Resource
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