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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure and opsin immunocytochemistry of the pineal complex of the larval Arctic charr Salvelinus alpinus: A comparison with the retina (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The fine structure and opsin immunocytochemistry of the pineal and parapineal organs of the salmonid fish Salvelinus alpinus, the landlocked Arctic charr, were studied and compared with the retina in various developmental stages, from prehatching to two-month-old. For opsin immunocytochemistry two polyclonal antibovine rhodopsin and the monoclonal antichicken opsin antibodies OS-2 (detecting blue and green pigments) and OS-1 (detecting green and red pigments) were used.Histologically, the pineal organ consists of nervous tissue like that of the retina. It is composed of photoreceptor pinealocytes, which formed axon terminals containing synaptic ribbons, on the dendrites and perikarya of secondary pineal neurons. Already in prehatching embryos, both the pineal and retinal photoreceptors display well-developed outer segments and form synaptic terminals. The distal part of the pineal organ differentiates earlier than its proximal stalk. The differentiation of the retina starts centrally, but the caudal and dorsal retinae are differentiated earlier than the rostral and ventral ones. At the end of the larval period, the lateral retina is still undifferentiated.In all stages studied, (rhod)opsin immunoreactivity was found in the outer segments of the pineal organ and rod-type retinal photoreceptors, a finding speaking in favour of the presence of the opsin of a rhodopsin/porphyropsin. Cone-type retinal photoreceptors identified morphologically in the pre- and posthatching stages were opsinimmunonegative with the four primary antisera used. This result suggests that in the charr the opsins of cone visual pigments differ in their chemical nature from those of rhodopsin/porphyropsin. The parapineal organ was opsin immunonegative. Using the monoclonal antibody OS-2 opsin immunoreactivity was also detected in inner segments, perikarya, and pedicles of rod-type photoreceptors of both retina and pineal organ of embryos and 1- to 4-day-old larvae. This may indicate a high level of opsin gene expression during photoreceptor growth around hatching. The well-developed pineal organ and its opsin content are discussed in connection with the photonegative behaviour of the larval charr.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00816.x
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  • 2
    Electronic Resource
    Electronic Resource
    GABA-immunoreactive intrinsic and -immunonegative secondary neurons in the cat pineal organ (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Vigh-Teichmann I, Petter H, Vigh B. GABA-immunoreactive intrinsic and 4mmunonegative secondary neurons in the cat pineal organ. J Pineal Res 199 1 : 10: 18-29.〈section xml:id="abs1-1"〉〈title type="main"〉Abstract:The pineal organ of the cat was studied by postembedding gamma-aminobutyric acid (GABA) immunocytochemistry. Two polyclonal rabbit GABA antisera were used with light microscopic peroxidase and electron microscopic immunogold techniques. A considerable number of intrinsic neurons are scattered in the proximal portion of the pineal organ. Some of the nerve cells were GABA-immunoreactive; other neurons as well as pinealocytes and glial/ependymal cells were immunonegative. A few GABA-immunoreactive neurons behaved like CSF-contacting neurons by penetrating the ependymal lining of the pineal recess. GABA-immunoreactive neurons were more frequently found in the subependymal region. Small bundles of thin immunoreactive unmyelinated and thick immunoreactive myelinated nerve fibers occurred in the proximal pineal, especially near the habenular commissure. There were synapses of various types between GABA-immunoreactive and -immunonegative fibers. Myelinated immunoreactive axons seemed to loose their sheaths after entering the organ. Axon-like processes of pinealocytes terminated on dendrites of immunonegative neurons present near the posterior and habenular commissures. The axons of these neurons were found to join the commissural fibers and may represent a pinealofugal pathway conducting information originating from pinealocytes. The pinealocytic axons forming ribbon-containing synapses on dendrites of secondary neurons speak in favor of the sensory-cell nature of the pinealocytes. The pinealopetal myelinated GABA-immunoreactive axons and the intrinsic “GABA-ergic” neurons are proposed to inhibit the action of intrapineal neurons on which the pinealocytic axons terminate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00005.x
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymhistochemische Studien am Nervensystem (1970)
    Springer
    Histochemistry and cell biology 21 (1970), S. 322-337 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Verhalten der AChE-Aktivität wurde in der periventrikulären Substanz des Zentralnervensystems von Fischen, Amphibien, Reptilien, Vögeln und Säugern enzymhistochemisch untersucht. In den bisher bekannten Liquorkontakt-Neuronengebieten — es handelt sich um Gebiete mit Nervenzellen, die durch ventrikuläre Portsätze und spezielle Nervenendigungen mit dem Liquor cerebrospinalis in direkter Berührung stehen- und auch in anderen periventrikulären Kerngruppen wurden AChE-positive Liquorkontakt-neurone gefunden. Die meisten derartigen, stark AChE-positiven Nervenzellen wurden im periventrikulären Höhlengrau des Hypothalamus und um den Zentralkanal des Rückenmarks der untersuchten Arten beobachtet. Im Telencephalon und Mesencephalon der Reptilien kamen nur vereinzelte AChE-positive Liquorkontaktneurone vor. Im Hypothalamus enthalten folgende Gebiete AChE-positive Liquorkontaktnervenzellen: Paraventrikularorgan, Recessus praeopticus-Organ, Nucleus praeopticus und paraventricularis, Nucleus infundibularis, Nucleus lateralis tuberis, Nucleus periventricularis hypothalami, Recessus lateralis der Amphibien, Recessus mamillaris der Fische und Saccus vasculosus. Im Rückenmark werden AChE-positive Liquorkontaktneurone um den Canalis centralis in Höhe der Urophyse und aller anderen Segmente des Rückenmarks beschrieben. Die AChE-Aktivität ist nicht nur in den Perikaryen, sondern auch in den ventrikulären Fortsätzen und Liquor-Endigungen der Zellen vorhanden. Die AChE-positiven Zellen der verschiedenen untersuchten Gebiete wurden in Hinsicht auf eine „cholinerge” Komponente des Liquorkontakt-Neuronensystems diskutiert.
    Notes: Summary The distribution of the activity of acetylcholinesterase (AChE) was studied enzyme-histochemically in the periventricular substance of the central nervous system of fishes, amphibians, reptilia, birds and mammals. In the liquor contacting neuronal territories known until now — the areas containing nerve cells which are directly contacting the cerebrospinal fluid by ventricular processes and special nerve terminals — and also in other periventricular nuclei, AChE-positive liquor contacting neurons were found. Most of these strongly AChE-positive nerve cells could be observed in the periventricular gray of the hypothalamus and around the central canal of the spinal cord of the species studied. In the telencephalon and mesencephalon of reptilia, only sporadic, AChE-positive liquor contacting neurons occured. In the hypothalamus, the following territories contained AChE-positive liquor contacting nerve cells: the paraventricular organ, preoptic recess organ, preoptic and paraventricular nuclei, infundibular nucleus, nucleus tuberis lateralis, the periventricular, hypothalamic nucleus, lateral recess of amphibians, mamillar recess of fishes, and the vascular sac. AChE-positive liquor contacting neurons were described around the central canal on the level of the urophysis and in all other segments of the spinal cord. Activity of AChE is not only present in the perikarya of the liquor contacting nerve cells, but also in their ventricular processes and liquor-terminals. The AChE-positive cells of the various territories investigated, were discussed with regard to a “cholinergic” component of the liquor contacting neuronal system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280902
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  • 4
    Electronic Resource
    Electronic Resource
    Enzymhistochemische Studien am Nervensystem (1968)
    Springer
    Histochemistry and cell biology 14 (1968), S. 352-365 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Zentralnervensystem des Regenwurmes Eisenia foetida wurden Phosphatasen, Esterasen und eine Peptidase histochemisch untersucht. Zwischen den Befunden an den einzelnen Ganglien des Nervensystems ergaben sich keine wesentlichen Unterschiede. Mit Ausnahme der im gesamten Regenwurm negativen Naphthol-AS-LC-acetatesterase, Leucinaminopeptidase und der alkalischen Phosphatasen, die nur in den coelomalen Deckzellen der bindegewebigen Kapsel eine deutliche Aktivität zeigten, waren alle von uns durchgeführten Enzymnachweise vor allem in den Gliazellen positiv. Die Reaktionen für saure Phosphatasen, Glucose-6-phosphatase, 5-Bromindoxylacetatesterase und Butyrylcholinesterase waren mäßig aktiv, während die Adenosintriphosphatase, α-Naphthylacetatesterase und Acetylcholinesterase eine starke Aktivität entwickelten. Lediglich einzelne Nervenzellen wiesen eine Reaktion für saure Phosphatasen und Glucose-6-phosphatase auf; die 5-Bromindoxylacetatesterase war nach 2 1/2 h Inkubation in allen Nervenzellen feingranulär. An der Grenze von Neuropil und Rinde bzw. verstreut im Neuropil sind Acetylcholinesterase-positive Strukturen auffindbar. Die enzymhistochemischen Ergebnisse stützen auch von diesen Enzymen aus die Auffassung einer trophisch-metabolischen Einheit zwischen Gliazellen und Neuronen.
    Notes: Summary The distribution of some phosphatases, esterases and one peptidase has been studied histochemically in the central nervous system of the earthworm (Eisenia foetida). There were no substantial differences between the results in the various ganglions of the nervous system. Almost all the enzyme reactions performed, were positive in glial cells, with the exception of naphthol AS-LC acetateesterase and leucine aminopeptidase being negative in the whole earthworm, and alkaline phosphatases that showed marked activity in the coelomal cells of the connective capsule. The reactions for acid phosphatases, glucose-6-phosphatase, 5-bromindoxyl-acetateesterase and butyrylcholinesterase were medium active, while adenosine triphosphatase, α-naphthylacetateesterase and acetylcholinesterase developed strong activity. Acid phosphatases and glucose-6-phosphatase reactions were shown only by single nerve cells; 5-bromindoxyl-acetateesterase was fine-granular in all neurons after 2 1/2 hrs of incubation. Acetylcholinesterase-positive structures could be found at the border of the neuropil and neuronal layer, and scattered in the neuropil. The enzyme-histochemical results from these enzymes, too, confirm the hypothesis of a trophic-metabolic unit made up of glial cells and neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304259
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  • 5
    Electronic Resource
    Electronic Resource
    Meningeal calcification of the rat pineal organ (1989)
    Springer
    Histochemistry and cell biology 91 (1989), S. 161-168 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface of the pineal organ of the rat is covered by a leptomeningeal tissue, the continuation of the corresponding meningeal layers of the diencephalon. The pineal leptomeninx consists of stratified arachnoid and of pia mater cells which follow the vessels into the pineal nervous tissue. The pineal arachnoid contains electron-lucent and electron dense cells differing from each other in their cytoplasmic components. Corpora arenacea of various size and density occur among these arachnoid cells and can grow into the pineal organ alongside pia mater tissue. Acervuli often form groups in circumscribed meningeal “calcification foci”. Concrements are absent or rare in the 1- and 2-month-old animal, while they are usually present in the 4- and 6-month-old rats. The electronmicroscopic localization of Ca-ions was studied in 2- and 4-month-old rats by potassium pyroantimonate cytochemistry. In the 4-month-old animals, arachnoid cells containing a varying amount of Ca-pyroantimonate deposits were found first of all around corpora arenacea, but there were also cells free of deposits in the close vicinity of the acervuli. Deposits were preferentially localized to the cytoplasm of electron dense arachnoid cells and to the cell membrane of electron-lucent cells. Most of the precipitates occurred in locally enlarged intercellular spaces. Here, microacervuli were found in 4-month-old animals suggesting that a calcium-rich environment was responsible for the appearance of the concrements. Intermediate stages between the small acervuli and large concentric corpora arenacea may indicate an appositional growth of the acervuli in the calcification foci. Occasionally, acervuli were also located inside meningeal cells. There was no sign of the formation of acervuli in the pinealocytes or elsewhere in the pineal nervous tissue proper, in the age interval (1- to 6-month-old animals) studied. These findings confirm the view that corpora arenacea can be produced in the rat by the pineal leptomeninx. The laboratory rat seems to be usefull in studying pineal calcification of the meningeal type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492390
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  • 6
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of Vitamin A in the retina and pineal organ of the frog,Rana esculenta (1988)
    Springer
    Histochemistry and cell biology 88 (1988), S. 533-543 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vitamin A immunoreactive sites were studied in the retina and pincal organ of the frog,Rana esculenta, by the peroxidase antiperoxidase, avidin-biotinperoxidase and immunogold methods. Indark-adapted material, strong immunoreaction was found in the outer and inner segments of the photoreceptor cells of both retina and pineal organ, as well as in the pigment epithelium, retinal Müller cells and pineal ependymal cells. Inlight-adapted retina, cones and green (blue-sensitive) rods were immunopositive. At the electron microscopic level, immunogold particles were found on the membranes of the photoreceptor outer segments as well as on the membranes of the endoplasmic reticulum and mitochondria. Individual retinal photoreceptor cells exhibited strong immunoreaction in the distal portion of the inner segment, the ciliary connecting piece and the electron-dense material covering the outer segment. In the pigment epithelium, the immunolabeling varied in intensity in the basal and apical cytoplasm and phagocytosed outer segments. The immunocytochemical results indicate that retinoids (retinal, retinol and possibly retinoic acid) are present not only in the photoreceptor cells of the retina but also in those of the pineal organ. The light-dependent differences in the immunoreactivity of vitamin A underlines its essential role in the visual cycle of the photopigments. Our results suggest that the pineal ependyma plays a role comparable to that of the Müller cells and pigment epithelium of the retina with regard to the transport and storage of vitamin A. The presence of a retinoid in nuclei, mitochondria and cytoplasmic membranes suggests an additional role of vitamin A in other metabolic processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570321
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  • 7
    Electronic Resource
    Electronic Resource
    Liquorkontaktneurone im Nucleus infundibularis (1970)
    Springer
    Cell & tissue research 108 (1970), S. 17-34 
    Details
    ISSN: 1432-0878
    Keywords: Nucleus infundibularis ; Reptiles ; Liquor contacting neurons ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Der Nucleus infundibularis verschiedener Reptilien wurde licht- und elektronenmikroskopisch untersucht. Zellen dieses Kernes entsenden Fortsätze durch ein mehrreihiges Ependym in den 3. Ventrikel und bilden dort freie, intraventrikuläre Nervenendigungen („Liquorkontakt-Nervenendigungen“, Lkne). Lichtmikroskopisch konnten in der Kerngruppe a) kleine, AChE-negative, toluidinblaue und b) große, AChE-positive, mit Toluidinblau hell erscheinende Nervenzellen unterschieden werden. Die knöpfchenförmigen LKNE weisen Elemente des endoplasmatischen Retikulums, freie Ribosomen, eine wechselnde Anzahl Mitochondrien, einzelne Lysosomen, asymmetrische Zilien (Typ 9+0) mit akzessorischem Basalkörper und Zilienwurzeln auf. Zwei LKNE-Typen sind unterscheidbar: a) LKNE mit granulierten Vesikeln mit einem Durchmesser von 800–1100 Å und b) LKNE mit großen, elektronendichten Granula (Durchmesser 1200–1600 Å). Im Lumen des 3. Ventrikels treten kleinkalibrige Axone auf, die kleine, granulierte Bläschen (Durchmesser 700–900 Å) enthalten und mit den LKNE des Nucleus infundibularis intraventrikuläre Synapsen bilden. Die Perikaryen des Nucleus infundibularis weisen ein reichliches endoplasmatisches Retikulum, zahlreiche Polyribosomen, Neurotubuli und Mitochondrien auf. Ähnlich wie bei den LKNE sind zwei Perikaryenarten zu unterscheiden: a) Perikaryen mit granulierten Vesikeln (Durchmesser 800–1100 Å) und b) solche mit elektronendichten Granula (1200–1700 Å). Außerdem kommen verschiedene Arten axosomatischer und axodendritischer Synapsen vor. Die Funktion der intraventrikulären Nervenendigungen und verschiedenen Synapsenarten in der Kerngruppe wird im Hinblick auf einen Informationsaustausch zwischen dem Liquor cerebrospinalis und dem Nucleus infundibularis diskutiert.
    Notes: Summary The infundibular nucleus of various reptiles was studied light and electron microscopically. Cells of this nucleus send processes through a stratified ependyma into the 3rd ventricle where they form free, intraventricular nerve terminals (“liquor contacting nerve endings”, LCNE). In the nucleus, two kinds of neurons could be distinguished light microscopically: a) small, AChE-negative, toluidine blue neurons, and b) large, AChE-positive cells staining light with toluidine blue. The club shaped LCNE contain elements of the endoplasmic reticulum, free ribosomes, a various amount of mitochondria, and single lysosomes. The terminals bear asymmetrical cilia (type 9+0) supplied with accessory basal bodies and rootlet fibres. Two kinds of LCNE are demonstrable: a) LCNE containing dense-core vesicles with a diameter of about 800–1100 Å, and b) LCNE with large, electron-dense granules (diameter about 1,200–1,600 Å). In the lumen of the 3rd ventricle, there occur small axons that contain small granulated vesicles (diameter about 700–900 Å), and that form intraventricular synapses with the LCNE of the infundibular nucleus. The perikarya of the infundibular nucleus contain an abundant endoplasmic reticulum, numerous polyribosomes, neurotubules and mitochondria. Similarly to the LCNE, two kinds of perikarya can be distinguished: a) perikarya containing granulated vesicles (diameter about 800–1100 Å), and b) perikarya with electron-dense granules (diameter about 1200–1700 Å). Furthermore, different types of axosomatic and axodendritic synapses occur. The function of the intraventricular nerve terminals and the different types of synapses in the nucleus is discussed with regard to an exchange of informations between the cerebrospinal fluid and the infundibular nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335940
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastruktur der Liquorkontaktneurone des Rückenmarkes von Reptilien (1970)
    Springer
    Cell & tissue research 109 (1970), S. 180-194 
    Details
    ISSN: 1432-0878
    Keywords: Liquor contacting neurons ; Spinal cord ; Reissner's fibre ; Reptiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Rückenmark der Reptilien kommen zwischen und unter den Ependymzellen des Zentralkanals bipolare Nervenzellen vor. Ihre Dendriten dringen in den Liquor cerebrospinalis ein und bilden dort charakteristische Nervenendigungen, die sich in lange, fingerförmige Fortsätze verzweigen. Letztere enthalten orientierte Filamente. In den Nervenendigungen findet man ebenfalls Filamente, multivesikuläre Körper und ferner Basalkörper, von denen Zilien und lange Zilienwurzeln ausgehen. Die Dendriten der Neurone sind durch desmosomenartige Strukturen mit den apikalen Abschnitten der benachbarten Ependymzellen verbunden und enthalten zahlreiche Mitochondrien und Golgi-Felder. Im Perikaryon der Neurone findet man ebenfalls ausgedehnte Golgi-Areale, ferner ein mit Ribosomen besetztes endoplasmatisches Retikulum, Mitochondrien, multivesikuläre Körper und granulierte Vesikel (Durchmesser um 870 Å). Der Neurit der Nervenzellen verläuft ependymofugal, in ihm kommen lange Mitochondrien und Neurotubuli vor. Auf den Dendriten, der Basis des distalen Fortsatzes, und den Perikaryen der Neurone können Synapsen beobachtet werden, deren präsynaptischer Bereich synaptische Vesikel, Mitochondrien und einige granulierte Bläschen (Durchmesser um 800 Å) aufweist. In einer Schnittebene dringen 5–6 Nervenendigungen in etwa gleicher Entfernung voneinander in den Zentralkanal ein. Unterhalb der intraependymalen Liquorkontaktneurone findet man eine weitere Nervenzellart, deren Zytoplasma heller ist und größere (Durchmesser um 1250 Å), den neurosekretorischen Elementargranula ähnliche Granula enthält. Die Ependymzellen des Zentralkanals besitzen zahlreiche Mikrovilli. Die Liquorkontakt-Nervenendigungen können mit dem Reissnerschen Faden in direktem Kontakt stehen. Die Hypothese wird diskutiert, daß die spinalen Liquorkontaktneurone — ähnlich denen der bisher beschriebenen Liquorkontaktgebiete — Rezeptoren sind, bei deren Funktion auch der Reissnersche Faden eine Rolle spielen kann.
    Notes: Summary In the spinal cord of reptiles, nerve cells are situated between and below the ependymal cells of the central canal. These neurons are bipolar; their dendrites protrude into the cerebrospinal fluid of the central canal where they build up characteristic nerve endings. These terminals ramify into long, finger-like processes containing oriented filaments. In the terminals, filaments, too, can be found besides of multivesicular and basal bodies, the latter giving rise to long rootlet fibres and cilia. The dendrite of the neurons is connected with the apical part of the neighbouring ependymal cells by desmosome-like structures, and it contains numerous mitochondria and Golgi areas. In the perikarya, enlarged Golgi areas, rough endoplasmic reticulum, mitochondria, multivesicular bodies and dense-core vesicles (diameter about 870 Å) are found. The neurite of the nerve cells that passes ependymofugally, contains long mitochondria and neurotubules. On the dendrite, the basis of the distal cell process and the perikarya of the neurons, synapses can be observed; their presynaptic cytoplasm contains synaptic vesicles, mitochondria and some dense-core vesicles (diameter about 800 Å). In one section, 5 to 6 nerve terminals protrude into the central canal in about equal distance from each other. Below these liquor contacting neurons situated intraependymally and described above, there is another type of nerve cells which cytoplasm is more electron lucent and contains larger (diameter about 1,250 Å) granules resembling neurosecretory granules. The ependymal cells of the central canal possess numerous microvilli. The liquor contacting nerve terminals may sometimes contact the Reissner's fibre directly. It is suggested that the spinal liquor contacting neurons — similarly to those of the liquor contacting territories described up to now — are receptors. In their function, also the Reissner's fibre may play a role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365240
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  • 9
    Electronic Resource
    Electronic Resource
    Licht- und elektronenmikroskopische Untersuchungen am Recessus praeopticus-Organ von Amphibien (1969)
    Springer
    Cell & tissue research 98 (1969), S. 217-232 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Recessus praeopticus-Organ (RPO) des 3. Ventrikels von Urodelen und Anuren wurde licht- und elektronenmikroskopisch untersucht. Es besteht aus einem speziellen Ependym und einer kleinzelligen Neuronengruppe, in der sich intraependymale, hypendymale und distale Nervenzellen unterscheiden lassen. Die Neurone senden Fortsätze in den Recessus praeopticus, wo sie freie, knöpfchenförmige Endigungen bilden. In den Nervenzellen, ventrikulären Dendriten und Liquorendigungen sowie in den peripheren Axonen ist fluoreszenzhistochemisch ein primäres Katecholamin, wahrscheinlich Noradrenalin, nachweisbar. Mit dem Elektronenmikroskop sind in den ventrikulären Nervenendigungen Mitochondrien, wenige Ergastoplasmacisternen, Mikrotubuli und „dense-core vesicles“ in wechselnder Menge und Größe (Durchmesser 500–850 Å) nachweisbar. Es ist charakteristisch für die Nervenendigung, daß sie meist über ein Zilium verfügt, von dessen Basalkörper und akzessorischem Zentrosom lange, quergestreifte Basalwurzeln ausgehen. Querschnitte atypischer Zilien (Typ 8+1, 9+0, 10+1, 20+0) werden beschrieben. Die ventrikulären Nervenfortsätze sind durch Zonulae adhaerentes mit den benachbarten Ependymzellen verbunden. Die Perikaryen der intraependymalen und hypendymalen Neurone enthalten „dense-core vesicles“ in wechselnder Menge. Die distalen Nervenzellen und ihre Fortsätze weisen relativ wenige Katecholamingranula auf. Im Neuropil wurden verschiedene Synapsen beobachtet, die wahrscheinlich unterschiedliche Funktionen ausüben. — An Hand der morphologischen Daten wird die Frage einer etwaigen Rezeptorfunktion des RPO diskutiert.
    Notes: Summary The preoptic recess organ (PRO) of the 3rd brain ventricle of urodela and anura has been studied by light and electron microscopy. — The PRO consists of a special ependyma and a parvocellular group of neurons. The latter is built up of intraependymal, hypendymal and distal nerve cells. The neurons send processes into the preoptic recess where they form free, club-like nerve terminals. In the perikarya, their ventricular dendrites and liquor endings as well as in their peripheral axons a primary catecholamine, probably noradrenaline, can be demonstrated by fluorescence histochemistry. As demonstrated electron microscopically, the ventricular nerve endings contain mitochondria, a few ergastoplasmic cisternae, microtubuli and dense-core vesicles of various amounts and size (500–850 Å). It characterizes the neurons that they mostly possess a cilium; its basal body and accessory centriol give rise to long rootlet fibers. Cross sections of atypical cilia (type 8+1, 9+0, 10+1, 20+0) are described. The ventricular nerve processes are connected with the surrounding ependymal cells by zonulae adhaerentes. The perikarya of the intraependymal and hypendymal neurons contain various amounts of dense-core vesicles. The distal nerve cells and their processes contain relatively few catecholamine granules. In the neuropil, different types of synapses are to be observed probably acting in different manner. — On the basis of the morphological data, the question of a receptor function of the PRO is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338326
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastruktur der spinalen Liquorkontaktneurone beim Krallenfrosch (Xenopus laevis) (1971)
    Springer
    Cell & tissue research 112 (1971), S. 201-211 
    Details
    ISSN: 1432-0878
    Keywords: Liquor contacting neurons ; Spinal cord ; Reissner's fibre ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Zwischen und unter den Ependymzellen des Zentralkanals des Rückenmarkes von Xenopus laevis kommen Nervenzellen vor. Die intraependymalen Neurone sind rundlich und stehen mit dem Liquor cerebrospinalis durch eine breite Oberfläche in Berührung, von der sich längere und kürzere Fortsätze und ein Cilium (Typ 9+2) in das Lumen erheben. Die hypendymalen Neurone sind bipolar; ihr Dendrit verzweigt sich im Liquor ebenfalls in fingerförmige Fortsätze. Die Liquorkontaktfortsätze beider Zelltypen sind von feinen Filamenten ausgefüllt. Der Reissnersche Faden lagert sich manchen Fortsätzen an. In den intra- und hypendymalen Perikaryen findet man neben endoplasmatischem Retikulum, Golgi-Arealen und Mitochondrien kleine dense-core Vesikel (Durchmesser 600–900 Å). Der distale Fortsatz beider Neurontypen hat Neuritennatur. Axone, die synaptische und granulierte (Durchmesser 800–1200 Å) Vesikel enthalten, bilden relativ wenige Synapsen mit den Liquorkontaktneuronen. Im hypendymalen Neuropil findet man multipolare Nervenzellen, die 1000–1200 Å große granulierte Vesikel enthalten. Aufgrund des morphologischen Bildes wird die mögliche Rolle der Liquorkontaktfortsätze und des Ciliums bei der Funktion der Liquorkontaktneurone diskutiert.
    Notes: Summary Nerve cells are situated between and below the ependymal cells of the central canal of the spinal cord of Xenopus laevis. The intraependymal neurons are round-shaped; they contact the cerebrospinal fluid by a large surface from which longer and shorter processes and a cilium (type 9+2) arise into the lumen. The hypendymal neurons are bipolar; their dendrite ramifies also into finger-like processes in the cerebrospinal fluid. The liquor contacting processes of both cell types contain fine filaments. The Reissner's fibre contacts some of the processes. In the intra- and hypendymal perikarya, small dense-core vesicles (diameter 600–900 Å) are found besides of endoplasmic reticulum, Golgi-areas and mitochondria. The distal process of both neuron types has neurite character. Axons containing synaptic and granulated (diameter 800–1200 Å) vesicles, form relatively few synapses with the liquor contacting neurons. In the hypendymal neuropile, multipolar nerve cells occur that contain granulated vesicles with a diameter of about 1000–1200 Å. On the basis of the morphological picture, the possible role of the liquor contacting processes and of the cilium in the function of the liquor contacting neurons are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331841
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