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  • 1970-1974  (5)
  • 1974  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Zoomorphology 79 (1974), S. 133-153 
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die licht- und elektronenmikroskopische Untersuchung der Prosomadrüsen der Spinnmilben Bryobia praetiosa, Bryobia rubrioculus und Tetranychus urticae (Tetranychidae, Trombidiformes) erbrachte die folgenden Ergebnisse 1. Im Prosoma liegen eine unpaare Tracheendruse mit eigenem Ausführgang und drei paarige Drüsen, die über einen gemeinsamen Sammelkanal, den podocephalischen Kanal, entleert werden. Zwei der podocephalischen Drüsen, die ventrale und die dorsale podocephalische Drüse, sind acinös, die dritte tubulös. 2. Die tubuläre Drüse ist eine Coxaldrüse. Sie haft sich in drei Abschnitte gliedern: proximalen Tubulus, Zwischenstuck and distalen Tubulus. Die einzelnen Abschnitte zeigen die fur transportaktive Zellen charakteristischen Feinstrukturen wie apikale Einstülpüngen und basale Zellwandeinfaltungen in unterschiedlichem Maße. Ein Sacculus ist nicht nachweisbar. 3. Die acinösen podocephalischen Drüsen enthalten zahlreiche Protein- Granula. Sie zeigen die feinstrukturellen Besonderheiten, die für proteinsynthetisierende Zellen typisch sind: große Nucleoli, große Mengen von Ribosomen, die bei der dorsalen Drüse meist an ER gebunden sind, während sie bei der ventralen vorwiegend frei im Cytoplasma liegen. 4. Die Tracheendrüse setzt sich aus zahlreichen Zellen zusammen, die untereinander durch Ausläufer stark verschränkt sind. In den Zellen liegen kleine helle Sekreteinschlüsse. 5. Neben den genannten Drüsen besitzt Tetranychus urticae ein weiteres Paar großer, einzelliger Drüsen, die an der Pedipalpenspitze ausmunden. Die Drüsenzellen sind fast völlig von großen Vakuolen ausgefiillt, die ebenfalls ein Eiweißsekret enthalten. 6. Diese Drüse ist die Spinndrüse. Ihr Sekret wird als Faden mit Hilfe einer hohlen Borste an jeder Pedipalpenspitze abgegeben. Drüse and Borste fehlen den nichtspinnenden Bryobia praetiosa und Bryobia rubrioculus.
    Notes: Summary The prosomal glands of the spider mites Bryobia praetiosa, Bryobia rubrioculus and Tetranychus urticae (Tetranychidae, Trombidiformes) were investigated with the light and electron microscopes. The following results were obtained: 1. An unpaired tracheal gland with its own secretory duct and three paired glands with a common duct, the podocephalic canal, are found in the prosoma. Two of the podocephalic glands, the ventral and dorsal, are acinous; the third is tubulous. 2. The tubular gland is a coxal gland. It can be divided into three parts: proximal tubule, intercalated segment and distal tubule. The individual parts exhibit to varying degrees the fine structure characteristic of transport-active cells, e.g. apical and basal invaginations. A saccule is not present. 3. The acinous podocephalic glands contain numerous protein granules. The secretory cells exhibit the fine structure which characterizes protein-secreting cells: big nucleoli, large amounts of ribosomes, which in the dorsal gland are usually attached to ER-membranes but occur freely in the cytoplasm of the ventral gland. 4. The tracheal gland consists of numerous cells, which are connected laterally by numerous interdigitations. The cytoplasm contains small pale secretory inclusions. 5. In addition to the above glands, Tetranychus urticae possesses an additional pair of large unicellular glands that open out at the tip of the pedipalpus. The glandular cells are almost completely filled with large vacuoles, which also contain a proteinaceous secretory product. 6. This gland is the silk gland. Its secretory product forms a thread which extends from the tip of each pedipalpus with the aid of a hollow hair. Gland and hair are absent in Bryobia praetiosa and B. rubrioculus which do not form webs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 148 (1974), S. 407-416 
    ISSN: 1432-0878
    Keywords: Tree frogs ; Adhesive digital pads ; Transmission and scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The digital pads of three tree-frogs (genus Rhacophorus) have been studied by transmission and scanning electron microscopy. The distal parts of the outermost epidermal cells are separated by wide gaps. The surface of these cells is characterized by stout microvillus-like processes. The apical plasma membrane is reinforced by a layer of electron-dense material attached to its inner side. The cytoplasm contains bundles of tonofilaments extending into the apical cellular processes, numerous ribosomes and abundant granular and vesicular inclusions. In the connective tissue under the epidermis mucous glands — characterized by granule-containing, mitochondria-rich and smooth muscle cells — and an extensive nerve plexus occur. The latter innervates the mucous glands and in addition consists of sensory fibres which have been found in connection with lamellated sensory corpuscles. In respect of the degree of adaption towards a tree-dwelling life, the excluvisely tree inhabiting species (Rhacophorus reinwardti) appears to be particularly advanced.
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  • 3
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Gymnophiona (Amphibia) ; Metamorphosis ; Ultrastructure ; Radioiodide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Different developmental stages of two species of the genus Ichthyophis have been investigated. In the late embryo the follicular cells of the thyroid gland exhibit various degrees of cytodifferentiation. Well differentiated cells show a polar organization and contain numerous granular inclusions, but a colloid-containing lumen is rare. Most cells at this stage contain large lipid inclusions. In young and older larvae the cells contain well-developed rough ER and Golgi systems, numerous mitochondria, and abundant granular and vesicular inclusions. Tentative identifications were made of primary lysosomes, secondary lysosomes, residual bodies, and two types of small apical vesicles—containing resorbed colloid or transporting material into the follicular lumen. In the larvae the number of apical microvilli is relatively high. The thyroid cells of the older larvae seem to contain more granular and vesicular inclusions than those of the younger larvae. In the adult the size of the follicles greatly increases, the height of the epithelium decreases, microvilli become rare, residual bodies are more frequent, and the small primary lysosomes are replaced by larger ones. Colloid droplets have been found only rarely in the cytoplasm of the thyroid cells of adult animals. In the immediate neighbourhood of the follicular epithelium, profiles of nerve fibres were found in all animals. Radioiodide investigations—measurements of conversion ratio and thyroid uptake factor—show, if compared with the results of corresponding studies in other amphibians, only relatively small differences between the larvae on the one hand and larvae and adults on the other. The absolute counts of the thyroid region are lowest in the adult and highest in the older larvae, shortly before metamorphosis. Furthermore our results indicate, on the basis of four animals tested, that in Ichthyophis the activity of the thyroid gland is temperature dependent. The results in Ichthyophis show that the classical stages of metamorphosis, in other amphibians characterized among other things by different levels of thyroid activity, are very indistinct in this animal.
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  • 4
    Publication Date: 1974-04-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 5
    Publication Date: 1974-12-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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