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  • 1
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Keywords: Spleen ; red pulp ; storage ; release ; morphology ; evolution ; structural characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light-dependent motor activity and phototactic behavior was investigated in 1) untreated, 2) blinded, and 3) blinded and pinealectomized eels (Anguilla anguilla L.). Neither blinding nor blinding combined with pinealectomy interfered with the observed nocturnal motor activity or the photonegative behavior characteristic for the untreated animals. However, an aluminum foil covering the skull of blinded animals altered the light-dependent motor activity pattern in contrast to blinded animals bearing a transparent plastic foil cover. Blinded animals with an aluminum foil covering the brain case exhibited a motor activity pattern resembling arrhythmicity. The motor activity pattern of 1) untreated, 2) blinded, as well as 3) blinded and pinealectomized eels followed an inversed light regime with a latency of about two days indicating that in the eel light is the dominatingZeitgeber triggering circadian motor activity patterns. The reported findings speak in favor of the existence of photosensitive areas in addition to the lateral eyes and the epiphysis cerebri. From the results of the covering experiments it is clear that these unknown photoreceptor sites must be located in the brain.
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  • 4
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Supravital recordings of spectral transmission in the brains of two species of teleosts (Anguilla anguilla, Ictalurus nebulosus), an amphibian (Rana temporaria), a reptile (Lacerta muralis), two species of birds (Passer domesticus, Columba livia), and a mammal (Phodopus sungorus) indicate that photons of longer wavelengths (700–750 nm) penetrate approximately 1,000 times more effectively into the hypothalamus than photons of shorter wavelengths (400–450 nm). The decrease in transmission from 750 to 400 nm is slightly interrupted by a plateau around 500 to 540 nm because of the transmission characteristics of hemoglobin. There is a small, ill-defined transmission minimum around 430 nm corresponding to the transmission minimum of melanin and hemoglobin (soret band). The high light sensitivity of deep diencephalic photoreceptors involved in the control of photoneuroendocrine events characteristic of some non-mammalian vertebrates suggests the occurrence of photopigment-containing receptors and nerve cells summating the input of several photoreceptors. However, in addition to photopigments, there may also exist other photosensitive compounds that mediate non-visual photoneuroendocrine responses.
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  • 5
    ISSN: 1432-0878
    Keywords: Pineal organ (epiphysis cerebri) ; Rana temporaria, Rana esculenta ; Neuronal organization ; Pineal tract ; Central nervous connexions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Problem der Zwischenneurone nimmt bei der Deutung der chromatischen und achromatischen Antworten der pinealen Sinnesorgane eine Schlüsselstellung ein. Frühere Ergebnisse schienen darauf hinzuweisen, daß der nervöse Apparat des Pinealorgans (Epiphysis cerebri) vonRana temporaria undRana esculenta bineuronal organisiert ist. Mit modifizierten Methylenblau- und Golgi-Methoden gelang es jetzt, die nervösen Strukturen der pinealen Rezeptoren und Nervenzellen präziser darzustellen. Das neurohistologische Bild der Epiphysis cerebri enthält auch Nervenzellen, die an Zwischenneurone denken lassen. Diese diffus verstreuten kleinen Elemente unterscheiden sich von den klassischen Typen der retinalen Bipolar-, Horizontal- und Amakrinzellen. Der Tractus pinealis vonR. temporaria undR. esculenta wird von Axonen großer multipolarer und kleiner, wenig verzweigter Ganglienzellen gebildet. Die zentrale Projektion dieser pinealofugalen (afferenten) Bahn ist von großem funktionellem Interesse. Nach vollständiger Unterbrechung des Tr. pinealis finden sich degenerierende Faserelemente innerhalb und am unteren Rand der Comm. posterior, in der Area praetectalis und in den Kernarealen des sog. „Zentralen Graus“. Keine degenerierenden Tractusfasern sind in der subependymalen Schicht und in den aminergen Kerngebieten des Mesencephalon zu beobachten. Die beschriebenen Verbindungen des Tr. pinealis könnten die anatomische Basis einiger lichtabhängiger (phototaktischer) Reflexe darstellen. Weitere Untersuchungen über die zentralnervöse Projektion des Tr. pinealis sind im Gang.
    Notes: Summary The problem of interneurons appears to be very important for the functional interpretation of the chromatic and achromatic responses of pineal sense organs. Previous results seemed to indicate a bineuronal chain in the pineal organ (epiphysis cerebri) ofRana temporaria andRana esculenta. Precise images of pineal receptors, neurons and their connexions were obtained in the present studies using methylene-blue and Golgi methods. A limited number of interneurons probably exist in theepiphysis ofR. temporaria andR. esculenta: the images of these scattered neurons were observed to differ from the classical bipolar, horizontal and amacrine cells of the amphibian retina. The pineal tract of R. temporaria andR. esculenta is formed by the axons of large multipolar and smaller scarcely ramified nerve cells. The central projection of this pinealo-fugal (afferent) pathway is of great functional interest. After complete surgical interruption of the pineal tract degenerating nerve fibers were traced in Nauta (Fink-Heimer) preparations. Degenerating fibers were observed within and beneath the posterior commissure, in the pretectal region and in the nuclear areas of the “periventricular gray”. The subependymal layer and the basal aminergic nuclei of the frog mesencephalon were always free of degenerating fibers. The anatomical connexion of the pineal tract described in this paper could serve as a basis for some light-dependent (phototactic) reflexes. Further investigations concerned with the central projections of the pineal tract are in progress.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 106 (1970), S. 556-583 
    ISSN: 1432-0878
    Keywords: Optic pathway ; Zonotrichia leucophrys gambelii (Aves, Passeriformes) ; Central connections ; Unilateral enucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Der Verlauf der Sehbahn und die Lokalisation der optischen Zentren wurden bei Zonotrichia leucophrys gambelii (nordamerikanischer Ammernfink) nach einseitiger Augenexstirpation mit den Techniken von Nauta-Fink-Heimer, Bodian und Bielschowsky erforscht. Die Untersuchungen erstreckten sich über einen Zeitraum von 3 bis zu 120 Tagen nach der Operation. Zonotrichia leucophrys gambelii besitzt ein für Vögel typisches visuelles System. Die Hauptmasse der Optikusfasern endet im Stratum griseum et fibrosum superficiale des Tectum opticum. Weitere zentrale Endgebiete sind: Nucleus geniculatus lateralis, Nucleus lateralis anterior, Nucleus superficialis synencephali, Nucleus externus, tectales Grau und Nucleus ectomamillaris als Kern der basalen optischen Wurzel. Alle Fasern werden im Chiasma opticum total gekreuzt, auch der Tractus isthmo-opticus, ein efferentes Bündel, dessen Ursprung im Nucleus isthmo-opticus zu finden ist. Dieses efferente Fasersystem läßt sich im Stumpf des durchtrennten N. opticus noch 120 Tage nach der Operation gut versilbern. Eine direkte Verbindung von Retina und Hypothalamus war lichtmikroskopisch nicht nachweisbar. Neurosekretorisch aktive Zellen des Hypothalamus können zwar einen engen räumlichen Kontakt mit den optischen Fasern haben, Synapsen sind aber an diesen Stellen nicht zu erkennen. Es werden passagere Opticusfasern beschrieben, die auf dem Weg zum Nucleus lateralis anterior und Nucleus superficialis synencephali den Hypothalamus durchsetzen.
    Notes: Summary The course of the optic pathways and the positions of the optic centers have been investigated with unilaterally enucleated white-crowned sparrows, Zonotrichia leucophrys gambelii, using the techniques of Nauta-Fink-Heimer, Bodian, and Bielachowsky. The investigation involved birds examined 3–120 days after enucleation. The white-crowned sparrow has a typically avian visual system. The major bundles of optic fibers terminate in the stratum griseum et fibrosum superficiale of the tectum opticum. Further terminal areas are the nucleus geniculatus lateralis, nucleus lateralis anterior, nucleus superficialis synencephali, nucleus externus, the “tectal gray”, and the nucleus ectomamillaris of the basal optic root. There is a complete crossing of all fibers in the chiasma, including those of the tractus isthmo-opticus, an efferent bundle with its origin in the nucleus isthmo-opticus. This efferent fiber system can be well impregnated in the stump of the sectioned optic nerve up to 120 days after the operation. No direct connection between the retina and hypothalamus could be demonstrated by light microscopy. Hypothalamic neurosecretory cells can occur in close contact with optic fibers but no synapses have been recognized. Some optic fibers pass through the hypothalamus enroute to the nucleus lateralis anterior and the nucleus superficialis synencephali.
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  • 7
    ISSN: 1432-0878
    Keywords: Pineal and parietal organs ; Lacerta vivipara ; Pre- and postnatal life ; Serotonin ; Noradrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Par la technique de Falck et Hillarp, nous avons étudié la localisation des monoamines indoliques et catéchniques épiphysaires durant la vie pré- et postnatale, chez Lacerta vivipara. A partir du stade 36 de l'embryogenèse, le traitement par les vapeurs de paraformaldéhyde induit en U.V. une fluorescence jaune, labile, dans l'épithélium épiphysaire dont la localisation est étudiée en fonction de la différenciation épiphysaire. L'analyse microspectrofluorimétrique des fluorophores jaunes permet de garantir, à tous les stades de la vie, un stockage de 5-HT et peut-être de 5-HTP, dans les cellules de type photorécepteur rudimentaire sécrétoire. Chez l'embryon, la confrontation des recherches histochimiques et ultrastructurale montre que les cellules «interstitielles» de type épendymaire (= «cellules de soutien») jouent un rôle dans le captage des acides aminés, dont les précurseurs de la sérotonine. Grâce à la technique de culture des embryons, en chambre noire, l'application de traitements pharmacologiques renseigne sur les modalités d'incorporation, et de stockage des dérivés indoliques. Le problème des systèmes enzymatiques impliqués dans la biosynthèse et le catabolisme de la sérotonine est discuté chez l'embryon. La fluorescence verte des fibres nerveuses pinéalopètes n'apparaît qu'au stade 39. L'analyse microspectrofluorimétrique des fluorophores verts, chez l'adulte, montre que le neurotransmetteur de ces fibres est la noradrénaline. L'apparition de la sérotonine et de ses rythmes éventuels ne dépendent donc pas de l'innervation adrénergique, aux jeunes stades de la vie embryonnaire. Dans les conditions normales et expérimentales, les monoamines (5-HTP, 5-HT et catécholamines) ne peuvent pas être mises en évidence dans l'oeil pariétal embryonnaire.
    Notes: Summary The distribution of monoamines (indole- and catecholamines) was studied in the pre- and postnatal pineal organ of the lizard Lacerta vivipara (J.) using fluorescence histochemistry. After formaldehyde treatment, a yellow (U.V.-labile) fluorescence first appears at stage 36 in the parenchyma. The distribution of this fluorescence is considered with regard to cellular differentiation. Microspectrofluorometric analysis of the yellow fluorophores shows a storage of 5-HT, and possibly 5-HTP, in secretory rudimentary photoreceptors throughout life. The fluorescence histochemistry and electron microscopy of the embryonic pineal organ indicates that the “interstitial” cells of the ependymal type play a role in the uptake of tryptophan and 5-HTP (precursors of serotonin). Dark chamber culture of embryos was used to clarify the incorporation and storage of indole compounds. The presence of enzymatic systems, involved in the metabolism of indoleamines is discussed. From stage 39 onwards a green fluorescence can be demonstrated in sympathetic nerve fibres running in the pineal capsule. Microspectrofluorometric analysis of the green fluorophores in the adult showed noradrénaline to be the normal neurotransmitter. Evidently the appearance of 5-HT during embryonic life does not depend on the adrenergic innervation of the pineal organ. In normal and experimental series, monoamines could not be demonstrated in the embryonic pariétal eye.
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  • 8
    ISSN: 1432-0878
    Keywords: Retinohypothalamic projection ; Passer domesticus ; Suprachiasmatic nucleus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The possibility of a direct retinohypothalamic projection was reinvestigated in Passer domesticus by electron microscopy following left unilateral retinectomy. To avoid misinterpretation of non-specific degeneration, the course of degenerative changes was observed at intervals of 6, 12, 24, 48 and 96 hours after operation. Of the hypothalamic areas examined in only one, the contralateral suprachiasmatic nucleus, was it possible to identify reliable indications of secondary anterograde degeneration comparable to those observed in the contralateral optic tectum. Single dark profiles within the supraoptic nucleus and the basal infundibular (tuberal) nucleus showed neither internal changes in structure nor an increase in number per unit area in retinectomized birds. Since photoperiodically induced gonadal growth occurs in totally blinded birds the functional significance of the retinohypothalamic projection to the suprachiasmatic nucleus is open to discussion.
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  • 9
    ISSN: 1432-0878
    Keywords: Salmo gairdneri (Teleostei) ; Pineal organ ; Photoreceptor cells ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im rasterelektronenmikroskopischen Bild des Pinealorgans vonSalmo gairdneri kann man drei verschiedene Außengliedtypen der Photorezeptoren unterscheiden. Diese Ergebnisse werden im Hinblick auf die Ultrastrukturkonzepte von Rüdeberg (1969) und Bergmann (1971) diskutiert. Rasterelektronenmikroskopische Studien erleichtern die anatomische Klassifizierung von pinealen Sinneszellen aufgrund ihrer Außengliedform.
    Notes: Summary The outer segments of pineal photoreceptor cells ofSalmo gairdneri were investigated with the scanning electron microscope. The scanning electron micrographs showed three different types of outer segments. These results are discussed with respect to the ultrastructural concepts of Rüdeberg (1969) and Bergmann (1971). Scanning electron microscopy permits better anatomical classification of pineal photoreceptor cells according to the form of their outer segments.
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  • 10
    ISSN: 1432-0878
    Keywords: Avian median eminence ; Noradrenergic innervation ; Microspectrofluorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The median eminence of duck, following freeze-drying and formaldehyde treatment (method of Falck-Hillarp), revealed within the subependymal layer of the internal zone a plexus of green fluorescent nerve fibers that encircled scattered neurons which apparently belong to the basal infundibular (tuberal) nucleus. Scarce fluorescent structures accompanied by a diffuse weak fluorescent reaction were seen in the reticular and palisade layers of the external zone. Fluorescent sympathetic fibers surrounded primary portal vessels in the perivascular space. Microspectrofluorimetric analysis revealed the presence of catecholamines in all fibers measured. After HCl treatment, the modifications of the excitation spectra indicated that the fibers in the subependymal layer of the inner median eminence contained noradrenaline. Dopaminergic fibers were not found in this region. The fluorescent contents of noradrenergic fibers was depleted by reserpine. After inhibition of dopamine-β-hydroxylase by FLA 63, some dopamine could be demonstrated in these noradrenergic fibers. After three successive intraventricular injections of 6-OH-dopamine their fluorescent contents disappeared. However, three months after this treatment some green fluorescent fibers were again seen in this location.
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