Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (8)
  • 1965-1969  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Studies on Feeding and Digestion in Protozoa. VII. Ingestion of Polystyrene Latex Particles and its Early Effect on Acid Phosphatase in Paramecium multimicronucleatum and Tetrahymena pyriformis (1965)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 12 (1965), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Food vacuole-free P. multimicronucleatum and T. pyriformis readily ingest non-nutritive Dow polystyrene latex particles (PLP) and form vacuoles containing PLP at a rate comparable to the formation of vacuoles containing bacteria. The particles aggregate within the vacuoles and are egested as balls of the size of the vacuoles. PLP containing vacuoles rapidly acquire acid phosphatase activity, which is demonstrated by histochemical (alpha-naphthyl phosphatehexazonium salt or lead phosphate) methods as a peripheric staining. The total activity of the cell does not significantly change as a consequence of PLP uptake as suggested by the histochemical preparations and confirmed in T. pyriformis by measuring the splitting of p-nitrophenyl phosphate at pH 5. Accordingly, no selection between nutritive and non-nutritive particles could be revealed. The vacuole formation is induced by the mechanical action of the particles. The appearance of acid phosphatase activity in the vacuole seems to be dependent on the vacuole formation and not on its content. This early appearance of activity is due to a redistribution of the preexistent activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1965.tb01807.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Electron microscopy of the paraventricular organ in the sparrow (Passer domesticus) (1967)
    Springer
    Cell & tissue research 80 (1967), S. 229-245 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Characteristics of the ependymal cells of the Paraventricular Organ (PVO) in the sparrow are strongly dilated ergastoplasmic cisternae filled with a moderately dense substance, the absence of cilia and a long basal process ending around capillaries. Elongated cells having a pale cytoplasm (“light cells”) are interposed between the ependymal cells. These cells protrude into the ventricle lumen with a bulbous cytoplasmic swelling; centrioles and several dense-core vesicles occur frequently in them. Two types of nerve cells have been identified in the PVO. The more superficial cells — called type-I neurons have a dendrite-like process which, after passing the ependymal layer reach the ventricle surface and end there freely with a bulbous swelling (“club”). The whole neuron contains dense-core vesicles of an average diameter of 840 Å; the extensive Golgi region is located in the dendrite. The larger type-II neurons situated in the deeper layers show a folded nuclear membrane, large mitochondria and rarely dense-core vesicles; the Golgi apparatus is enclosed in the perikaryon. The nerve cells are embedded in a feltwork of glial and neural processes the latters showing often synaptic (axodendritic) junctions. The majority of the synapses are supposed to occur between the axon-like processes of the typeI neuron and dendrites of the type-II neuron. Axo-somatic synapses can be found not infrequently on the perikarya of the latters. The nature of the free ventricular endings of the neurons and the possible function of the PVO are discussed in the text.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337459
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Phospholipidgranula im verhornenden Oesophagusepithel (1966)
    Springer
    Cell & tissue research 73 (1966), S. 205-219 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Epithel des Meerschweinchenoesophagus fanden wir mit Ausnahme des Stratum corneum in jeder Schicht 0,1–0,3 μ große, lamellär-strukturierte Granula. Die Granula werden meistens von einer Membran (unit-membrane) umgeben, die ein lamelläres System in sich einschließt, das eine Periodizität von 60–70 Å aufweist und aus dunklen und hellen Lamellen besteht. Unsere Annahme, daß die Granula Phospholipide enthalten, wird durch die Beobachtung unterstützt, daß die Lokalisation der lichtmikroskopisch durchgeführten Baker-Reaktion vollkommen mit der Verteilung der lamellären Granula im elektronenmikroskopischen Bild übereinstimmt. Nach Pyridinextraktion ist die Baker-Reaktion negativ, während im elektronenmikroskopischen Material an Stelle der Granula nur Vakuolen zu finden sind. Die Granula erscheinen im Stratum germinativum meistens in Verbindung mit dem Golgiapparat und entleeren sich in Höhe des Stratum granulosum in den interzellulären Raum. Zwischen den Lamellen des Stratum corneum ist das Material der Granula als eine homogene, dunkle, amorphe Deckschicht vorhanden. Ihre Aufgabe besteht wahrscheinlich in der Steigerung der Resistenz der Hornschicht.
    Notes: Summary Lamellated granules of 0,1 to 0,3 μ in diameter are consistently found in all strata of the keratinizing epithelium of the guinea pig oesophagus. The granules are surrounded by a single membrane (unit membrane) and contain a lamellated system consisting of dark and light bands showing a periodicity of 60 to 70 Å. The supposed phospholipid nature of the granules was supported by the positive Baker-reaction at the light microscope level. The distribution of the Baker-positive substance was identical with that of the lamellated granules at the electron micrograph. After extraction with pyridin, the Baker-reaction turned out to be negative while on the electron micrographs the substance of the lamellated granules was lost. The granules first appear near the Golgi region of the stratum germinativum and are emptied into the extra-cellular space at the level of the stratum granulosum. The substance of the granules, after having lost their lamellated structure, remains between the keratinized layers as a homogenous, dense material. Its function probably consists in increasing the resistance of the cornified layer against chemical agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334864
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The effect of prolonged light-deprivation on the fine structure of planarian photoreceptors (1968)
    Springer
    Cell & tissue research 90 (1968), S. 507-518 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Planarians (Dugesia tigrina) were kept for 1, 2 and 3 weeks in total darkness and the fine structure of the eyes was investigated. After fixation in osmium, the photoreceptors (retinal clubs) showed a progressive disintegration of the microvilli membranes into vesicles and tubules. Although the vesicular transformation of the membranes was not found in glutaraldehyde-prefixed experimental animals, it could not be detected in the osmium-fixed controls either. Consequently the vesicular transformation must be regarded as a meaningful artefact due to membrane instability induced by prolonged deprivation of light. After 3 weeks in the darkness strong atrophy and degeneration of the retinal clubs was observed both in osmium and glutaraldehyde-fixed specimens resulting in a decrease of the club to about one fifth of its original size. As a result large empty spaces appeared between rudimentary retinal clubs and the whole eye became shrunken. When animals kept for 4 weeks in the darkness were exposed to normal light conditions, a rapid regeneration of the microvilli was observed together with an increasing stability of the membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339499
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Untersuchungen an in vitro gezüchteten Thymusepithelzellen und Hassallschen Körperchen (1965)
    Springer
    Cell & tissue research 65 (1965), S. 915-929 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung In vitro gezüchtete Thymusepithelzellen des jungen Meerschweinchens zeigen ein stark entwickeltes Ergastoplasma, dessen Zisternen eine mäßig elektronenstreuende Substanz enthalten. Die peripheren Zellschichten der Hassallschen Körperchen haben eine normale Struktur. In den mehr zentral gelegenen Zellen erscheinen typische Tonofilamente; der Inhalt der Zisternen des Ergastoplasmas ist vermehrt, so daß sie runde, sackartige Gestalt annehmen. Charakteristisch für diese Zellen sind ferner runde, dunkle Körper, die wahrscheinlich mit Lysosomen identisch sind. Das Material im Zentrum des Hassallschen Körperchens besteht aus degenerierten Zellen; nur die Zellmembranen und Desmosomen bleiben hier längere Zeit erhalten. In diesem Gebiet sind die Zellreste mit zahlreichen feinen Filamenten erfüllt. Die morphologischen Vorgänge im Hassallschen Körperchen werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319310
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Electron microscopic observations on myoid cells of the frog's thymusDedicated to Professor Neubert on the occasion of his 70th birthday. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 165 (1969), S. 329-341 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Myoid cells of the thymus of hibernating frogs were examined by electron microscopy. This cell type is represented by immature, fully-developed and degenerating cell forms. The immature forms are mainly located at the surface, whereas the developed ones are found in the inside of the thymus. A peculiar type of immature cell containing no thick filaments, but possessing a rich sarcoplasmic reticulum among the thin filaments is described. The developed myoid cells have a myofibrillar apparatus showing regular cross-striations. The myofibrils are arranged in concentric layers around the nucleus. The proposed role and origin of myoid cells and their probable connection with myasthenia gravis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091650302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Untersuchungen am Organon vasculosum laminae terminalis der Ratte (1969)
    Springer
    Cell & tissue research 102 (1969), S. 483-506 
    Details
    ISSN: 1432-0878
    Keywords: Organon vasculosum ; Laminae terminalis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das OVLT stellt jenen Abschnitt der Lamina terminalis dar, der durch eine eigentümliche, reiche Vaskularisation auffällt. Die von der Basalmembran bedeckte äußere Hirnoberfläche dringt an einer oder mehreren Stellen tief und spaltenartig in das OVLT ein. Dieser Spalt, der Bindegewebselemente und Gefäße enthält, verzweigt sich immer mehr und bildet ein aus 0,1–0,2 μ breiten Spalten bestehendes, labyrinthartiges System. Zum großen Teil füllen Gefäße vom Kapillartyp die größeren bindegewebigen Räume aus. Das Endothel der Kapillaren ist allgemein dünn und z. T. fenestriert. Die Bindegewebsräume und mit ihnen die Gefäße können sich dem Ventrikel derart nähern, daß sie von ihm durch nur eine einzige kubische Ependymzelle getrennt werden. Der Stützapparat des Organs wird in erster Linie von den Ependymzellen gebildet. Ihre langen basalen Fortsätze durchschneiden die Gehirnwand im Gebiet des OVLT und nehmen mit ihren Endigungen am Aufbau der Wand der Bindegewebsspalten und der äußeren Hirnoberfläche teil. In einem Teil der Ependymfüße findet man zahlreiche längliche, lysosomenartige Körper. Häufig kommen in die Tiefe der Substanz des OVLT eingedrungene Ependymzellen vor, welche nicht selten Zilien enthalten. Unter den Gliazellen konnten in erster Linie Astrozyten identifiziert werden. Die lichtmikroskopisch im OVLT beschriebenen sog. Parenchymzellen erweisen sich im Elektronenmikroskop als kleine, primitive Neurone. Ein großer Teil der Nervenfasern des Neuropils enthält granulierte Vesikel (Durchmesser zwischen 650 und 950 Å), die im allgemeinen eine runde oder ovoide Gestalt besitzen, obwohl auch tubulös ausgezogene Formen vorkommen. Die Nervenfasern welche die granulierten Vesikel enthalten, verlaufen nahe zur Kammeroberfläche, allgemein in der Längsachse des OVLT, wobei sie die länglichen Ependymzellen überkreuzen; in der Nähe der Endigung der basalen Ependymfortsätze wenden sie sich parallel zu letzteren und endigen zusammen mit ihnen frei am Rand der Bindegewebsspalten. Je ein solches, aus basalen Ependymfasern und Axonen bestehendes Bündel wird mehr oder weniger vom bindegewebigen Spalt umfaßt. Die Axonendigungen enthalten außer den granulierten Vesikeln und Mitochondrien auch zahlreiche synaptische Vesikel. Einige freie Axonendigungen wurden auch auf der freien Oberfläche des OVLT gefunden. Die Frage nach der Funktion des Organs wird an Hand der elektronenmikroskopischen Befunde diskutiert. Es wird für möglich gehalten, daß humorale Faktoren — ähnlich wie in der Eminentia mediana — aus den Axonendigungen in die Blutbahn gelangen; darauf scheinen die freien Endigungen am Rande des bindegewebigen Spaltensystems, die granulierte und synaptische Vesikel enthalten und die teilweise fenestrierten Kapillaren hinzuweisen, welche den aufgezweigten Bindegewebsraum „drainieren“.
    Notes: Summary OVLT is that part of the terminal plate which is characterized by its rich vascular supply. The brain surface covered by a basement membrane forms deep, cleft-like invaginations containing vessels and connective tissue elements. These connective tissue spaces dividing into 0.1 to 0.2 μ end branches are parts of a labyrinthic system in the interior of the organ. The vessels, mostly of the capillary type, are situated in the main clefts; their endothelium often shows fenestration. Some of the capillaries may approach the ventricle to such an extent that they are separated from it by a single ependymal cell. The supporting apparatus of the OVLT is mainly represented by elongated ependymal cells. Their long basal processes traverse the terminal plate to take part with their foot-like endings in the formation of the brain surface and that of the connective tissue spaces. Groups of special ependymal cells often exhibiting cilia may occur in the interior of the organ. Glial cells are mainly represented by astrocytes. The so-called parenchymal cells described in the light microscopy can be identified as small, primitive neurons. A great part of the nerve fibres in the OVLT contains granulated vesicles the diameter of which varies between 650 and 950 Å. The nerve fibres are mainly running vertically between the ependymal processes while at their terminal portion they assume a parallel course to the ependymal processes and end with them at the margin of the connective tissue spaces. Besides granulated vesicles, these free axon terminals contain numerous synaptic-like vesicles and several mitochondria. Some of the free terminals may occur also on the outer surface of the OVLT. The possible functions of the organ are discussed on the basis of the present findings. The hypothesis is raised that — similarly to the median eminence — humoral controlling factors may be released into the vessels. This hypothesis seems to be supported by the presence of free axon terminals containing granulated and synaptic vesicles and the existence of numerous, partly “fenestrated” capillaries draining the connective tissue spaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...