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  • Development  (9)
  • Springer  (9)
  • American Physical Society (APS)
  • Blackwell Publishing Ltd
  • 2000-2004
  • 1970-1974  (9)
  • 1971  (9)
Collection
Publisher
  • Springer  (9)
  • American Physical Society (APS)
  • Blackwell Publishing Ltd
Years
  • 2000-2004
  • 1970-1974  (9)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 7 (1971), S. 267-276 
    ISSN: 1432-0827
    Keywords: Tech ; Development ; Enamel ; Enzyme ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'activité en naphtylamidase est étudiéc au niveau des incisives et molaires de rat, à divers stades de développement. Du L-leucyl-4-methoxy-2-naphtylamide, du L-alanyl-4-methoxy-2-naphtylamide, du L-leucyl-2-naphthylamide et du DL-alanyl-2-naphtylamide sont utilisés comme substrats: du bleu rapide B et du grenat rapide GBC sont employés comme sels de diazonium. Le naphtylamidase n'est pas visible au niveau de dents, en voie de dévelopment, au cours de la formation matricielle de l'émail. A la fin de ce stade, le naphtylamidase est présent au niveau de l'extrémité distale des améloblastes, près de la surface de l'émail. L'activité enzymatique reste identique jusqu'au moment de la fusion de l'épithélium dentaire et de l'épithélium buccal, au moment de l'éruption de la dent dans la cavité buccale. On ne rencontre pas de naphtylamidase au niveau d'autres tissues dentaires; cependant une activité marquée est observée dans les ostéoclastes au niveau des surfaces de résorption de l'os alvéolaire, entourant les dents, en voie de développement et d'éruption, et dans certaines régions du tissu conjonctif.
    Abstract: Zusammenfassung Die Aktivität der Naphthylamidase wurde in den Backen- und Schneidezähnen von Ratten in verschiedenen Entwicklungsstufen studiert. Als Substrate wurden L-leucyl-4-methoxy-2-naphthylamid, L-alanyl-4-methoxy-2-naphthylamid, L-leucyl-2-naphthylamid und DL-alanyl-2-naphthylamid verwendet; als Diazoniumsalze dienten Echtblau B und Echt-Granat GBC. Naphthylamidase konnte während der Schmelzmatrixbildung im Zahn nicht nachgewiesen werden. Nach Abschluß dieser Phase erschien Naphthylamidase in den distalen Enden der Ameloblasten, nahe bei der Schmelzoberfläche. Die Enzymtätigkeit blieb am selben Ort lokalisiert, bis das Zahnepithel, im Augenblick wo der Zahn in die Mundhöhle durchstößt, in das Mundepithel überging. Naphthylamidase wurde in anderen Zahngeweben nicht gefunden, aber eine deutliche Aktivität konnte in gewissen Bezirken des Bindegewebes sowie in den Osteoklasten der resorbierenden Oberflächen vom alveolären Knochen festgestellt werden, welcher die sich bildenden und die hervorstoßenden Zähne umgibt.
    Notes: Abstract Naphthylamidase activity was studied in rat molar and incisor teeth at different stages of development. L-leucyl-4-methoxy-2-naphthylamide, L-alanyl-4-methoxy-2-naphthylamide, L-leucyl-2-naphthylamide and DL-alanyl-2-naphthylamide were used as substrates and Fast blue B and Fast Garnet GBC as diazonium salts. Naphthylamidase was not demonstrable in the teeth during enamel matrix formation. After the termination of this stage, naphthylamidase was present in the ameloblasts in their distal ends close to the enamel surface. The enzyme activity retained this localization until the dental epithelium fused with the oral epithelium at the time of tooth eruption into the oral cavity. Naphthylamidase was not found in other dental tissues, but marked activity was found in osteoclasts at the resorbing surfaces of alveolar bone surrounding the developing and erupting teeth and in certain areas of the connective tissue.
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  • 2
    ISSN: 1432-0878
    Keywords: Chemoreceptor ; Locusta ; Fine structure ; Development ; Moulting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basic structure of the terminal sensilla of Locusta migratoria resembles that of Schistocerca gregaria. There are commonly six or ten neurons whose dendrites extend almost to the opening of the peg. Proximally the dendrites are clothed by a neurilemma cell which also encloses a basal cavity through which their ciliary region passes. The tormogen cell encloses the receptor-lymph cavity and actively secretes material into it. The receptor-lymph cavity and the basal cavity are quite separate. The development of new pegs at a moult is described. After apolysis the scolopale extends across the subcuticular space and protects the dendrites, which remain in a functional condition until shortly before ecdysis. As the trichogen cell grows out to form a new peg the tip is surrounded by a mass of electron-dense material, probably derived from the receptorlymph cavity. The function of this material is unknown. Regeneration of the dendrites is considered. The possible mechanism by which the tip of the peg opens and closes is considered and the general structure of the organule is discussed in relation to functioning.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 113 (1971), S. 558-563 
    ISSN: 1432-0878
    Keywords: Pterin layer ; Pigmentation ; Dermis ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the pterin layer was investigated in both wild type Rana pipiens and Rana pipiens homozygous for the speckle mutant gene. No difference in morphology of the layer was noted between the wild type and mutant. The layer lines the outer surface of the stratum compactum of the dermis and separates this stratum from the stratum spongiosum. The pterin layer consists of extra-cellular material and contains membrane-bounded granules filled with fine spicules. Many of the spicules are somewhat similar in appearance to the initial calcification loci present in developing membrane bone. The layer first appears in the tadpole at approximately stage 14 (Taylor and Kollros, 1946); subsequent developmental stages are described.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 113 (1971), S. 157-173 
    ISSN: 1432-0878
    Keywords: Prostate ; Development ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The postnatal development of the rat prostate has been studied with the electron microscope. Major developmental changes begin during the second week after birth and involve organelles associated with the formation of secretions. The amount of granular endoplasmic reticulum and the size of the Golgi complex increase greatly. Large vacuoles that probably contain secretory material are formed, and the lumen of the prostatic acini appears to contain secreted material. Large lysosomes with polymorphic interiors are present as early as 10 days after birth, and they become numerous by the end of the third week. Differences in fine structure between the different lobes of the prostate are detectable in 10–14 day old rats. The subsequent differentiation of the granular endoplasmic reticulum into the forms characteristic of the different prostatic lobes is described. The initial changes in the prostate occur in advance of sexual maturity of the animal, and the adult appearance of the gland is attained by 4–5 weeks after birth.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 114 (1971), S. 546-556 
    ISSN: 1432-0878
    Keywords: Microvilli ; Small intestine ; Brush border ; Development ; Golgi apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Frage, auf welche Weise die Enterocyten des fetalen Rattendünndarms das für die Mikrovillibildung benötigte Membranmaterial liefern, wurde elektronenmikroskopisch untersucht. Es wird angenommen, daß hufeisenförmige Strukturen, die aus mit elektronendichtem Material bedeckten Elementarmembranen bestehen und möglicherweise Längsschnitten durch kappenförmige Gebilde entsprechen, in das apicale Plasmalemm eingebaut werden und für die Bildung der Mikrovillispitzen verantwortlich sind. Diese Annahme gründet sich in erster Linie auf die Feststellung eines nahezu identischen Durchmessers von „Hufeisen“ und Mikrovilli, auf die Lokalisation der „Hufeisen“ im Terminalgespinst und ihr zahlenmäßiges Verhalten während der Mikrovillibildung. Die „Hufeisen“ entstehen im Golgi-Apparat.
    Notes: Summary The origin of membranes required for the formation of microvilli has been investigated electronmicroscopically in enterocytes of fetal rat small intestine. It is assumed that horseshoe-like structures consisting of unit membranes covered with electron-dense material, which probably represent longitudinal sections through cap-like structures, are incorporated into the apical cell membrane and give rise to the tips of microvilli. This assumption is based chiefly on the almost identical diameters of “horseshoes” and microvilli, the localization of “horseshoes” in the terminal web, and the time of appearance and disappearance of “horseshoes” with regard to development of microvilli. There are indications that the “horseshoes” originate in the Golgi apparatus.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 115 (1971), S. 396-415 
    ISSN: 1432-0878
    Keywords: Human pineal organ ; Development ; Innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This investigation is concerned with pineal organs of human embryos 60 to 150 days old. At every stage central nerve fibres enter the pineal organ by way of the habenular commissure, but are restricted to the pineal's proximal part. On about the 60th day of the development the sympathetic nervus conarii grows into the distal pole of the pineal organ from a dorso-caudal direction and plays the predominant part in the innervation of the pineal organ. After penetrating, it soon branches out and forms a network in the pineal tissue. Much later, not until the 5th embryonic month, sympathetic nerves appear accompanying the supplying vessels in the perivascular spaces. After a short time these nerves pierce the outer limiting basement membrane and penetrate the parenchyma. Towards the end of the 5th embryonic month the axons of the sympathetic nerves form varicosities containing clear and dense core vesicles. At this point large amounts of laminated granules appear primarily in cell processes, probably of pinealocytes. Isolated granules also occur in the varicosities of axons. The granules encountered here are most likely secretory granules.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 118 (1971), S. 579-592 
    ISSN: 1432-0878
    Keywords: Bye ; Innervation ; Adrenergic ; Development ; Manuals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of adrenergic nerves to the anterior eye segment was studied in human and guinea-pig embryos. Adrenergic terminals had already appeared in the earliest human embryos available (4–6 cm). They first appeared mainly in nerve trunks in the primitive chorioid, especially in the region of the developing ciliary body. Adrenergic nerves then grow into different structures of the eye as these develop, but typical terminals in contact with effector cells appeared late during the development, about the 25–30 cm stage. No adrenergic nerves were observed in the chamber angle. Corneal adrenergic nerves (also intraepithelial terminals) appeared much more frequently in embryos than in adults. No adrenergic neurons were observed in the retina. In the guinea-pig, the first adrenergic fibres were observed at about gestation day 35. The general principle of the development was very similar to that of the humans. At gestation day 45 to 50, the supply of adrenergic fibres was essentially that of the adult animal, except that the corneal adrenergic fibres were increasing until just before birth and that the adrenergic terminals of the chamber angle appeared shortly before term.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 119 (1971), S. 208-226 
    ISSN: 1432-0878
    Keywords: Median eminence ; Hypophysial portal vessels ; Pars distalis ; Ultrastructure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve fibres containing granular vesicles first appear in the median eminence of the rat on the 16th foetal day while secretory granules in the cells of the adenohypophysis are not present till the 17th foetal day. These observations suggest that the differentiation and early activity of pars distalis cells may depend on substances elaborated at nerve terminals in the median eminence. Although the loops of the primary plexus of portal vessels do not develop until the 4th postnatal day, substances released by nerve fibres in the neurohypophysis could reach the pars distalis through vessels already present at the 15th foetal day in the mesenchyme between the diencephalon and the adenohypophysis. This view is supported by the fact that the earliest cells to exhibit ultrastructural evidence of secretory activity are in the rostral pole of the pars distalis, the first region of the gland to become vascularized. The earliest granules to appear in the cells of the pars distalis correspond to those which are considered to contain mucoprotein hormones; somatotrophin type granules were seen only in postnatal tissues. The finding that, in the median eminence, the development of granular vesicles precedes that of agranular vesicles is discussed with reference to the times at which neurosecretory materials and monoamines become detectable in the region.
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  • 9
    ISSN: 1432-0878
    Keywords: Synaptic vesicles ; Development ; Golgi apparatus ; Smooth endoplasmic reticulum ; Zinc iodide-osmium technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Routine electron microscopy and a zinc iodide-osmium tetroxide technique (ZIO), recently found to be specific for synaptic vesicles, were used to study the origin of synaptic vesicles during postnatal development in the lumbosacral enlargement of the albino rat. In immature nervous tissue, a large number of vesicles, indistinguishable from synaptic vesicles (S vesicles), were found in the Golgi apparatus and in different portions of the axon where they were often intermingled with elements of the smooth endoplasmic reticulum (SER). Ten to twenty percent of these S vesicles within the Golgi apparatus as well as the majority of these vesicles in all parts of the axon were positive to ZIO. Much of the SER in axons was also positive. The number of vesicles and elements of the SER showed some decrease in the non-terminal portion of axons on day 21 and even more of a decrease in adult neurons. These data suggest that synaptic vesicles are produced in the Golgi apparatus and SER in immature neurons. The decrease in S vesicles and SER in adult neurons suggests a drop in synaptic vesicle production after synaptogenesis has ended. In addition, the material that has been studied shows that ZIO staining is not limited to synaptic vesicles during development since oligodendroglia and endothelial cells are also stained during this period.
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