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  • Articles  (369)
  • Ultrastructure  (369)
  • Springer  (369)
  • Nature Publishing Group
  • 1975-1979  (369)
  • Medicine  (369)
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  • Articles  (369)
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  • Springer  (369)
  • Nature Publishing Group
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  • 1
    Electronic Resource
    Electronic Resource
    Coquille de l'oeuf de caille: Étude ultrastructurale et cristallographique (1978)
    Springer
    Calcified tissue international 25 (1978), S. 145-159 
    Details
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010763
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural and microanalytical aspects of developing osteodentin in rat incisors (1977)
    Springer
    Calcified tissue international 24 (1977), S. 215-222 
    Details
    ISSN: 1432-0827
    Keywords: Mineralization ; Osteodentin ; Intracellular ; Ultrastructure ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Newly formed osteodentin obtained from the anterior extremities of fetal or young rat incisors was observed by means of electron microscopy and electron probe X-ray microanalysis. Cells related to osteodentin formation frequently showed membrane bound intracellular bodies containing varying amounts of fine, needle-shaped crystals, which were identified as apatite. The intracellular clusters of apatite crystals were extruded from the cells through membrane fusion or cellular degeneration. These extracellular clusters seemed to be gradually incorporated into the mineralizing collagenous matrix, which developed around them. Frequent occurrence of dense, dotshaped or filamentous profiles suggested that the dense bodies seen in the perinuclear regions or in the Golgi area were the sites of crystal formation. Energy dispersive X-ray point analysis showed that the intracellular or extracellular apatite clusters contained sulfur in a concentration higher than was present in the mineralizing collagenous matrix. Furthermore, wave dispersive X-ray line analysis showed that the concentration of sulfur was higher in the osteodentin matrix than in the dentin matrix. The sulfur detected is presumed to be contained in acid mucopolysaccharides, which were distributed more heavily in the osteodentin matrix than in the dentin matrix. On the basis of these data, it was concluded that the unique chemical and structural characteristics of the osteodentin result primarily from the incorporation of apatite clusters of intracellular origin and associated acid mucopolysaccharides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223319
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the biology of fish bone. III. Ultrastructure of osteogenesis and resorption in osteocytic (cellular) and anosteocytic (acellular) bones (1979)
    Springer
    Calcified tissue international 28 (1979), S. 43-56 
    Details
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteogenesis ; Fish bone ; Osteocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The comparative ultrastructure of fish bone osteogenesis and resorption induced by scale removal was described in the osteocytic (cellular-boned)Carassius auratus and the anosteocytic (acellular-boned)Tilapia macrocephala. Osteocytes, present in osteocytic bone, were lacking in anosteocytic bone. In osteocytic bone the osteoblast secreted a collagenous preosseous matrix in which it became enmeshed and then was termed a preosteocyte. When the preosseous matrix mineralized, the preosteocyte was termed an osteocyte and was completely surrounded by bone. In anosteocytic bone the osteoblasts receded from the mineralizing front and never became trapped as osteocytes. During resorption, types A and B resorptive cells, present in both bone types, invaded the matrix and demineralized the osseous zone. These cells were characterized by large amounts of granular endoplasmic reticulum and intracellular inclusions containing crystal-like material. Although functionally similar to mammalian osteoclasts, these cells lacked a characteristic ruffled border and were not multinucleated. The osteocytes of cellular bone did not appear to be involved during demineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441217
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  • 4
    Electronic Resource
    Electronic Resource
    The ultrastructure of the zygospore in Endogone flammicorona Trappe & Gerdemann (1976)
    Springer
    Mycopathologia 59 (1976), S. 117-123 
    Details
    ISSN: 1573-0832
    Keywords: Ultrastructure ; Zygospore ; Mycorrhizal fungus ; Flaming crown
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ultrastructural organization of the spores of the sporocarp of Endogone flammicorona was studied. Two types of organization are described. Initially the spore possessed a vacuolate protoplasm and was bound by two cell wall layers. The spore was surrounded by a hyphal mantle formed of a sheet of vacuolized hyphae with uniformly thin walls. Secondly, although the ultrastructural features of the spore appeared the same, it was now surrounded by a hyphal mantle with unevenly thickened walls (i. e., the so-called flaming crown) due to the gradual and irregular deposition of granules and lamellae. This crown gives the spore its most commonly observed morphological feature and is the preminent character employed taxonomically to speciate Endogone flammicorona Trappe & Gerdemann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493564
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure, histology, and innervation of the mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi (1978)
    Springer
    Calcified tissue international 26 (1978), S. 271-282 
    Details
    ISSN: 1432-0827
    Keywords: Shell formation ; Free nerve endings ; Ultrastructure ; Lymnaea stagnalis ; Biomphalaria pfeifferi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi was investigated with histochemical and ultrastructural methods. The mantle edge gland, which is involved in shell formation, consists of the periostracal groove and the belt. This belt appears to be composed of various regions. In the area of the periostracal groove a number of subepithelial gland cell types occur; these release their products into the groove. Between the groove cells ciliated free nerve endings terminate; the corresponding perikarya occur in the subepidermal connective tissue. Also in the posterior belt region free nerve endings were observed between the epithelial cells; in addition, a particular type of subepithelial gland cell was found in this area. The epithelial cells of this part of the belt have the ultrastructural characteristics of ion and water transporting cells; they are probably involved in calcium deposition and resorption. The possible role of the free nerve endings and of the subepithelial gland cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013270
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  • 6
    Electronic Resource
    Electronic Resource
    The ultrastructure of the sinus gland of Gammarus oceanicus (Crustacea: Amphipoda) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 557-564 
    Details
    ISSN: 1432-0878
    Keywords: Sinus gland ; Gammarus ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sinus gland of Gammarus oceanicus, like that of other crustaceans, is composed of three elements: neurosecretory axons, glial cells and stromal sheath. Five neurosecretory axon types are identified on the basis of granule diameter, shape, and electron density, and axon matrix density. Exocytosis appears to be the major release mechanism of neurosecretory material. The preterminal regions of neurosecretory axons contain axoplasmic reticulum and neurotubules. Their arrangement in the axon and relationship with one another suggest a transport function. Multilamellar bodies are found in the terminal regions of neurosecretory axons. They arise from mitochondria and may be involved in granulolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219838
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  • 7
    Electronic Resource
    Electronic Resource
    Biosynthesis of the basal lamina as a result of interaction between thyroid and mesenchymal cells in culture (1979)
    Springer
    Cell & tissue research 200 (1979), S. 69-81 
    Details
    ISSN: 1432-0878
    Keywords: Thyroid follicular cells ; Basal lamina, biosynthesis ; Cellular interaction ; Cell culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Porcine thyroid cells were cultured alone or in mixed cultures with mesenchymal cells. The formation of a basal lamina in vitro was investigated ultrastructurally. Follicular reassociation of thyroid cells occurred in both types of culture; however, it was followed by formation of the basal lamina only when mesenchymal cells were present. The present findings suggest an epithelial origin of the basal lamina resulting from an interaction with mesenchymal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236888
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural identification of non-adrenergic, non-cholinergic nerves in the rat anococcygeus muscle (1979)
    Springer
    Cell & tissue research 200 (1979), S. 257-271 
    Details
    ISSN: 1432-0878
    Keywords: Anococcygeus muscle ; Innervation ; P-type nerves ; Purinergic nerves ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the rat anococcygeus muscle has been investigated ultrastructurally following fixation with a modified chromaffin reaction for the demonstration of biogenic amines (Tranzer and Richards, 1976). Three types of nerve profiles were revealed: (1) 60–70 % of the profiles are adrenergic; (2) less than 5% of the profiles appear to be cholinergic; (3) up to 40% of the profiles are distinguished by the presence of a characteristically high proportion of electron-opaque, chromaffin-negative vesicles, 85–110nm in diameter. This third type of profile was not affected by 6-OHDA, and is considered to represent the non-adrenergic, non-cholinergic inhibitory innervation of this tissue. Because of the morphological similarity of this nerve type, apart from the smaller vesicle size, to classical peptidergic nerve endings, they have been termed “small p-type” (sp-type). These results are discussed in relation to a previous report describing only two types of nerve profiles in this tissue (Gillespie and Lüllmann-Rauch, 1974).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236418
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  • 9
    Electronic Resource
    Electronic Resource
    A stereological ultrastructural study of stimulated peritoneal macrophages in the germ-free mouse (1979)
    Springer
    Cell & tissue research 200 (1979), S. 299-309 
    Details
    ISSN: 1432-0878
    Keywords: Germ-free mice ; Inflammation ; Macrophages ; Peritoneum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Peritoneal macrophage ultrastructure was analysed stereologically in germ-free mice given a single intraperitoneal injection of sterile, pyrogen-free saline. Thus the stimulant was non-particulate, non-antigenic and inorganic, and effects of immune reactions were minimal. Macrophages were recovered 1, 6, 24 and 72 h after stimulation. A sequence of structural alterations is reported which may be fundamental to macrophage activation. The plasma membrane and nuclear envelope increased in area within only 1 h of saline injection. During the next 5 h loss of plasma membrane, probably by pinocytosis, caused cellular “rounding” and clear-cut alteration in surface configuration. At the same time lysosome-like granules enlarged but decreased in number. By 24 h most cellular structures and compartments (including the plasma membrane) were enlarged. Morphological evidence of nuclear activation accompanied a rather modest enlargement of the nucleus at this stage. The RER hypertrophied last and must, therefore, be judged sufficient in resident macrophages to support the initial growth response which results after stimulation. Thus hypertrophy was observed eventually in every structure examined. Even the minimally activated macrophages resident in the peritoneum of germ-free mice respond readily to stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236422
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  • 10
    Electronic Resource
    Electronic Resource
    An ultrastructural analysis of the gametes and early fertilization in two bivalve molluscs, Chama macerophylla and Spisula solidissima with special reference to gamete binding (1977)
    Springer
    Cell & tissue research 182 (1977), S. 469-489 
    Details
    ISSN: 1432-0878
    Keywords: Fertilization ; Molluscs ; Spermatozoon ; Oocyte ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural investigation of the gametes and their interaction during the early events of fertilization in molluscs has been performed. A gamete binding event involving large numbers of sperm has been identified and examined in detail. The surface of the oocyte is projected into numerous microvilli which extend through the vitelline envelope. Tufts of fibrillar material radiate from the tips of these microvilli, forming a layer external to the vitelline envelope. The acrosomal vesicle of the mature spermatozoon contains two major components, which function differently during fertilization. The vesicle is indented at its adnuclear surface, constituting a preformed acrosomal tubule. This tubule does not elongate during the acrosome reaction. Completion of the reaction results in the formation of an extracellular coat, derived from one component of the acrosomal vesicle, on the anterior surface of the sperm. Sperm-egg binding is accomplished by an association of the extracellular coat on the reacted sperm and the fibrous tufts on the tips of the microvilli of the oocyte. Evidence that gamete membrane fusion occurs by fusion of the acrosomal tubule and a microvillus is presented. These observations provide a generalized pattern of molluscan fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219830
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  • 11
    Electronic Resource
    Electronic Resource
    The role of the haemocytes of Clitumnus extradentatus in haemolymph coagulation (1977)
    Springer
    Cell & tissue research 182 (1977), S. 513-524 
    Details
    ISSN: 1432-0878
    Keywords: Haemocytes ; Insects ; Haemolymph coagulation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron-microscopic observations of the blood cells (haemocytes) of the stick insect Clitumnus extradentatus in vitro showed that two morphologically distinct cell types, the cystocytes and granular cells are involved in haemolymph coagulation. Both these cell types contain a variable number of electron-dense granules which upon release cause progressive coagulation and precipitation of the haemolymph. In the cystocytes this release is extremely rapid (30–60s) while in the granular cells it only occurs after 1–2min in vitro. The role of these cells in haemostasis is discussed together with the possible significance of the involvement of two cell types in the coagulation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219833
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  • 12
    Electronic Resource
    Electronic Resource
    Ultrastructural tracer studies on the permeability of the Malpighian tubule of the Pill Millipede, Glomeris marginata (Villers) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 549-556 
    Details
    ISSN: 1432-0878
    Keywords: Malpighian tubules ; Millipede ; Ultrastructure ; Tracers ; Formed bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The electron-dense tracers ferritin, and iron-dextran, and the protein horseradish peroxidase, have been used to investigate the ultrastructural basis of permeability in the upper and lower segments of the Malpighian tubules of Glomeris marginata. All these materials were able to cross the basal lamina and enter the tubule lumen of the upper segment, and it was established that horseradish peroxidase was able to enter the channels which interrupt the apical junctions. In the upper segment, ferritin, iron-dextran, and horseradish peroxidase are all taken up and accumulated within intracellular vesicles. In the lower segment ferritin and iron-dextran enter the cells but become generally distributed over the cyptoplasm, as well as entering membrane-bounded vacuoles. The behaviour of horseradish peroxidase could not be assessed owing to the presence of endogenous peroxidase activity in the cells. After fixation by direct application of glutaraldehyde to the undissected tubules, the extracellular spaces contained large numbers of membrane-bounded vesicles. The significance of these observations is discussed in relation to the physiological activities of the tubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219837
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  • 13
    Electronic Resource
    Electronic Resource
    Quantitative morphological study of smooth muscle cells of the guinea-pig taenia coli (1976)
    Springer
    Cell & tissue research 170 (1976), S. 161-186 
    Details
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Intestine ; Ultrastructure ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A quantitative study of muscle cells of the guinea-pig taenia coli is reported. Stereological methods were used on electron micrographs and phase contrast micrographs. Smooth muscle cells of taeniae fixed under 1 gram load were about 515 μm long. Muscle cell volume was about 3,500 μm3 and cell surface 5,300 μm2. About 168,000 caveolae were found at the surface of each muscle cell, covering about 29 percent of its surface. They produced a 73 percent increase of the cell membrane compared to a smooth-surfaced cell. The ratio surface-to-volume is about 1∶0.67 if the geometrical surface is considered, or 1∶0.39 if the total surface of the cell membrane (including the caveolae) is considered. Mitochondria constituted 3.5–4 percent of the cell volume. A few nexuses were observed, both between two muscle cells and between a muscle cell and an interstitial cell. In serial sections septa of connective tissue and groups of muscle cells were found to disappear within few tens of microns or to merge with other septa, and the taenia did not appear to be divided into clear-cut muscle cell bundles. Bundles of smooth muscle cells were seen passing from the taenia to the underlying circular muscle. The transverse sectional area of the taenia ranged between 0.14 and 0.39 mm2; it showed about 526 blood vessels · mm-2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224297
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  • 14
    Electronic Resource
    Electronic Resource
    Structural changes in smooth muscle cells during isotonic contraction (1976)
    Springer
    Cell & tissue research 170 (1976), S. 187-201 
    Details
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Contraction ; Taenia coli ; Ultrastructure ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Smooth muscle cells of the guinea-pig taenia coli were studied in light and electron microscopy, in condition of mild stretch or of isotonic contraction. During contraction the cells increase in transverse sectional area and their packing density passes from 94,000 · mm-2 to 18,000 · mm-2. The percentage increase in transverse sectional area of the taenia is approximately the same as the percentage decrease in length. Measurements of cell transverse sectional area suggest that the individual cells shorten and fatten more than the taenia as a whole. Whereas stretched muscle cells run parallel to each other and show a fairly smooth surface, isotonically contracted cells are twisted and entwine around each other. Their surfaces are covered with myriad processes and folds. Longitudinal, transverse or oblique stripes are seen in light microscopy in the contracted muscle cells and it is suggested that they are related to the characteristics of the cell surface. In electron microscopy a complex pattern of interdigitating finger-like and laminar processes is observed. Caveolae are mainly found on the evaginated parts of the cell surface, dense patches are mainly (but not always) found on the invaginated parts. Desmosome-like attachments between contracted cells are frequent. The collagen fibrils run approximately parallel to the stretched muscle cells; on the other hand, they run obliquely and transversely around the isotonically contracted cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224298
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  • 15
    Electronic Resource
    Electronic Resource
    Early effects of nerve growth factor on adrenergic neurons: An electron microscopic morphometric study of the rat superior cervical ganglion (1975)
    Springer
    Cell & tissue research 158 (1975), S. 543-553 
    Details
    ISSN: 1432-0878
    Keywords: Sympathetic ganglia ; Nerve growth factor ; Enzyme induction ; Ultrastructure ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve cells of the superior cervical ganglion of young rats (20 g body weight) were investigated electron microscopically 6 h, 24 h, 48 h and 5 days after subcutaneous injection of nerve growth factor (10 μ/g body weight every 24 h). By means of a planimetric method with high accuracy significant changes of the Nissl substance and the Golgi apparatus could be demonstrated as early as 6 h after injection. Within the Nissl bodies both the density of bound ribosomes on the cisternae of the rough endoplasmic reticulum and the density of free ribosomes and polysomes decreased in a given field. This finding reflects a rearrangement of the Nissl substance and a spreading over larger areas of the cytoplasm, indicating an activation of the ribosomal system. The Golgi apparatus, in particular its outer part, increases in volume with time of nerve growth factor treatment. On the other hand, the total cell volume does not show significant changes before 48 h of nerve growth factor treatment. At this time an increase in the cytoplasmic volume can be seen, whereas the nuclear volume remains unchanged. The possibility of correlations of the present findings with data from biochemical studies done under similar experimental conditions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220218
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  • 16
    Electronic Resource
    Electronic Resource
    Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) (1975)
    Springer
    Cell & tissue research 159 (1975), S. 245-266 
    Details
    ISSN: 1432-0878
    Keywords: Neuromuscular junctions ; Rete synapticum ; Development ; Antheraea ; (Lepidoptera) ; Trophic action ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of neuromuscular connections on developing dorsolongitudinal flight muscles was studied in the moth Antheraea polyphemus, Undifferentiated membrane contacts between axon terminals and muscle-fiber anlagen are present in the diapause pupa. They persist during the period of nerve outgrowth, which probably provides a pathway of contact guidance. By the 4th day of adult development some of these contact areas have differentiated into structures similar to neuromuscular junctions although differentiation of muscle structure does not start earlier than the eighth day. Dense-cored vesicles are abundant in many axon terminals at the beginning of development. They later decrease in number quite rapidly. The significance of the above-mentioned early junctions, their possible mode of action and the role of the dense-cored vesicles are discussed. It is proposed that they exercise a stimulating (trophic) influence on the growth of the undifferentiated muscular tissue. The imaginai neuromuscular junctions are formed during the second half of adult development. Clusters of vesicles and electron-dense depositions along the inner face of the axolemma seem to initiate junction formation. Glial processes then grow between axoand sarcolemma and divide the large contact area into several small segments. Mutual invaginations and protrusions of the sarcolemma and the glial cell membrane subsequently form an extensive “rete synapticum.” Six days before eclosion the glial and sarcoplasmic parts of the rete synapticum are similar in size. Up to eclosion, all glial processes shrink and increase in electron density. Most of the observations are discussed also in relation to findings in vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00219160
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  • 17
    Electronic Resource
    Electronic Resource
    The ultrastructure of normal and glycerol treated muscle in the ghost crab, Ocypode cursor (1975)
    Springer
    Cell & tissue research 159 (1975), S. 369-378 
    Details
    ISSN: 1432-0878
    Keywords: Crab muscle ; Excitation-contraction coupling ; Glycerol treatment ; Horseradish peroxidase ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of normal and glycerol treated fibers of the closer muscle of the ghost crab, Ocypode cursor, was studied. The muscle is composed of presumably phasic (short sarcomeres) and tonic (long sarcomeres) fibers, the latter greatly predominating. Horseradish peroxidase (HRP) was used as an extracellular tracer to delineate the tubular system (TS), and to determine to what extent this system becomes detached from the extracellular space as a result of glycerol treatment. Sarcolemmal clefts invade deeply into the muscle at Z-lines and I-bands; tubules invaginate into the muscle from the clefts and from the surface sarcolemma at the Z-lines, A-I overlaps and A-bands. A tubules are in frequent diadic or tetradic contact with the sarcoplasmic reticulum (SR), whereas Z tubules appear to be randomly associated with SR, terminal cisterns (TC) and Z-line fibrils. When HRP was administered to normal muscle, black reaction product was found adjacent to the outer surface of the sarcolemma, within the clefts and within profiles of the TS throughout the tissue. In glycerol treated muscle peripheral vacuolation frequently occurred; black reaction product penetrated only as far as the vacuoles and into dilated Z-line tubules, but was virtually absent from the rest of the TS. This lack of continuity between the extracellular space and the A tubules indicated disruption or constriction of the A tubules as a result of glycerol treatment, although Z tubule contact with the extracellular space appeared unimpaired. These findings provide ultrastructural correlates of the electrophysiological changes produced by glycerol treatment of the closer muscle of the ghost crab (Papir, 1973), namely, interference with excitation-contraction (e-c) coupling. The random association of the Z tubules with SR and TC, and their resistance to disruption by glycerol treatment, tend to endorse the claims that the Z tubules in crustacean muscle are not directly involved in e-c coupling (Brandt et al., 1965; Peachey, 1967; Selverston, 1967).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221783
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  • 18
    Electronic Resource
    Electronic Resource
    Studies on the fine structure of the cuticle of Porcellidium, crustacea Copepoda (1975)
    Springer
    Cell & tissue research 159 (1975), S. 399-412 
    Details
    ISSN: 1432-0878
    Keywords: Porcellidium (copepode) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Deux espèces de Porcellidium ont été examinées en microscopic à balayage et sur coupe avec les techniques habituelles (P. viride provenant de Banyuls-sur-mer, Méditerranée et P. fimbriatum de Roscoff, Manche; ces deux espèces vivent sur les Algues vertes du genre Ulva). Nous avons retrouvé les ultrastructures classiques de la cuticule, observées dans les principaux groupes de Copépodes. Quatre caractères nouveaux distinguent la cuticule dorsale des Porcellidium: 1. Différenciation d'un système de microvillosités externes, avec un niveau dense aux électrons, très contrasté par rapport aux extrémités d'où semblent partir de fins filaments englobant une population assez dense de Bactéries. 2. Cette plage de microvillosités recouvre un relief assez particulier de la procuticule, évoquant par ses cratères un paysage lunaire. 3. Présence de canaux cytoplasmiques ramifiés et terminés par une expansion arrondie, sous l'épicuticule. 4. Existence d'un système de vésicules reliant la base des microvillosités aux extrémités renflées des canaux cytoplasmiques. L'association des Bactéries est régulière et une grande proportion de celles-ci est en cours de cytolyse. La système de microvillosités et de canaux ne nous parait pas étranger à la présence de cette population bactérienne.
    Notes: Summary Two species of Porcellidium have been studied by scanning and transmission electron microscopy: P. viride from Banyuls-sur-mer, Mediterranian Sea and P. fimbriatum from Roscoff, English Channel. Both species live on green Algae of the genus Ulva. We confirmed previous descriptions of the cuticular ultrastructure in the main groups of Copepods. Four new characteristics however were shown to occur in the backcuticle of Porcellidium: 1. The presence of a system of highly differentiated external microvilli showing electron dense basal portions and less electron dense tips, from which thin filaments project towards a large population of Bacteria associated with the Copepod. 2. The surface of the cuticle resembles a lunar landscape with craters. The sheet of microvilli closely follows the contour of the cuticle. 3. The presence of branched cytoplasmic canals with swollen extremities (beneath the epicuticle) extending from the epidermal cells. 4. Systems of vesicles lying between the bases of the microvilli and the expansions (ampullae) at the tip of the cytoplasmic canals. The association of Bacteria with the cuticle is constant and many of these are apparently undergoing cytolysis. The system of microvilli and of cytoplasmic canals are apparently related to the presence of the bacterial microflora.
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    Ultrastructure of the Budgerigar testis during a photoperiodically induced cycle (1975)
    Springer
    Cell & tissue research 159 (1975), S. 541-550 
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    ISSN: 1432-0878
    Keywords: Testis ; Budgerigar ; Photoperiod ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spermatogenesis in the Budgerigar can be arrested by reducing the birds' photoperiod to 8 hours of daylight or less. When this occurs, Sertoli cell cytoplasm shows a great increase in the size and number of residual bodies, while the smooth endoplasmic reticulum is reduced. If the bird is kept at 8 hours of daylight for some weeks large lipid droplets are seen in Sertoli cytoplasm, and degenerated spermatids are apparently phagocytosed. The interstitium shows fewer active Leydig cells, a paucity of lipids and occasional ovoid mitochondria. The basal lamellae of the tubule which are thick and convoluted before and during spermatogenesis become thinner and straighter. It is thought that these morphological changes reflect changes in metabolic activity.
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    Morphology of the perivascular regions of the rat neural lobe in relation to hormone release (1975)
    Springer
    Cell & tissue research 159 (1975), S. 551-561 
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    ISSN: 1432-0878
    Keywords: Neurohypophysis, rat ; Exocytosis ; Blood vessels ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neural lobes of rats subjected to dehydration by drinking 2% saline for four days were examined electron microscopically and compared to untreated controls. The ultrastructure of the blood vessels and the tissues surrounding them were examined and it was found that, although few exocytotic figures could be seen in either group of animals, a significantly larger (P〈0.01) number of small vesicles were found in nerve endings adjacent to the perivascular space in the saline treated group when compared to nerve endings not closely associated with blood vessels. No differences were found in the control group of animals, which supports the suggestion that the vesicles could arise from a membrane recapture process.
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    Structure and regeneration of the eyes of strombid gastropods (1976)
    Springer
    Cell & tissue research 171 (1976), S. 259-271 
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    ISSN: 1432-0878
    Keywords: Eyes ; Strombus ; Regeneration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tips of the eyestalks of three species of strombid gastropods were amputated and the structure of the fully developed eye investigated. The retina contains at least two types of cell: sensory cells bearing long tufts of microvilli with a central cytoplasmic core, and pigment cells with short microvilli. New eyes became visible at the tips of the eyestalk stump 5–16 days after amputation. When the regenerated eyes first appear, they consist of hollow balls of cells with a pigment lined cavity; two types of retinal cells are already distinguishable but their microvilli and cilia are small and sparse. The microvillous tufts and sensory cell contents develop quickly and about 14 days after their first appearance, the eye is a fully formed but miniature organ.
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    URL: http://dx.doi.org/10.1007/BF00219410
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    Gap junctions in hemodichorial and hemotrichorial placentae (1976)
    Springer
    Cell & tissue research 171 (1976), S. 305-315 
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    ISSN: 1432-0878
    Keywords: Chorioallantoic placenta ; Gap junctions ; Diaplacental transport ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gap junctions were found to be a constant feature of chorioallantoic placentae with two or three trophoblastic layers. The gap junctions connect layers I and II in hemodichorial and layers II and III in hemotrichorial placentae. Although the gap junctions vary in form and in the packing density of membrane-associated particles, they cover an extensive surface area in all species examined. The gap junctions always connect adjacent membranes of two trophoblastic layers, which show no evidence of micropinocytotic activity; at least one of these trophoblastic layers is syncytial. It is therefore concluded that the gap junctions play an important role in diaplacental transport. We consider that gap junctions act as molecular sieves, resulting in limitations in the transport of large molecules. The passage of small molecules, on the contrary, would be facilitated by the gap junctions.
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    URL: http://dx.doi.org/10.1007/BF00224656
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    Electron microscopic observations on the innervation of the sphincter of oddi in the dog (1975)
    Springer
    Cell & tissue research 161 (1975), S. 167-176 
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    ISSN: 1432-0878
    Keywords: Sphincter Oddi (Dog) ; Innervation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure and acetylcholinesterase activity of the intrinsic innervation of the sphincter of Oddi of eight adult dogs was studied by electron microscopy. A rich distribution of unmyelinated axons embedded individually or as groups within Schwann cell cytoplasm (“innervation fasciculée”), is to be observed. A few myelinated fibres were also observed. Many of the axons are acetylcholinesterase-positive. Three main types of nerve terminals are distinguished according to their vesicle populations. Individual nerve cells or small groups of nerve cells were scattered between the smooth muscle bundles and in the lamina glandularis mucosae. The cytoplasm of some neurons contains many electron dense spherical bodies resembling “myeloid bodies”, and many lysosomes. Nerve terminals synapse onto both neuronal perikarya and their dendrites. Within the nerve fascicles, close appositions between the terminals occur frequently probably representing the most peripheral inter-neuronal integrative link in the neural regulation of the function of the sphincter of Oddi. — The gap between nerve terminals and smooth muscle cells usually measures several thousands of Å. Closer appositions are seldom seen, and no synaptic complexes can be observed.
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    URL: http://dx.doi.org/10.1007/BF00220365
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    The structure of the rectal papilla in a parasitoid hymenopteran Nasonia vitripennis (Walker) (Hymenoptera Pteromalidae) (1975)
    Springer
    Cell & tissue research 161 (1975), S. 413-419 
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    ISSN: 1432-0878
    Keywords: Rectal papilla ; Insects ; Hymenoptera ; Cell Types ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the rectal papillae of the parasitoid hymenopteran, Nasonia vitripennis (Walk), is described. These organs in this insect consist of four distinct cell types arranged as a closed, hollow cone. The majority of the cells are present in the raised cone, and are characterised by large numbers of mitochondria arranged in a membranous labyrinth. A series of cells form a collar around the base of the cone. Junction cells have been identified which are present at the point of insertion of the cone into the rectal epithelium. The base of the cone consists of cells with elaborately folded plasma membranes facing both the central cavity of the cone, and the haemolymph. The structure of this rectal papilla is compared with those found in other insects.
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    URL: http://dx.doi.org/10.1007/BF00220008
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    Effects of barbiturates on ultrastructure and polymerization of microtubules in vitro (1975)
    Springer
    Cell & tissue research 162 (1975), S. 35-47 
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    ISSN: 1432-0878
    Keywords: Microtubules ; Barbiturates ; Axonal transport ; Polymerization ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Barbiturates were examined for in vitro effects on ultrastructure of the frog sciatic system and polymerization of microtubules (MT) in a brain supernatant. Exposure for 5–17 h to 2.0 mM barbiturates caused a considerable loss of MT in ganglionic cell bodies and sciatic axons. This was mostly followed by a proliferation of 10 nm filaments. Under similar conditions treatment with 1 mM NaCN or 0.1 mM 2,4-DNP did not change the number or ultrastructure of MT and filaments. Eight barbiturates, varying in binding ratios to serum albumin and partition coefficients, were tested for effects on polymerization of MT using viscometry. Inhibitory effects were found which correlated with their reported ability to bind to albumin and brain fractions. Dimethylsulphoxide and ethanol were used as solvents for some of the barbiturates. These solvents at 1% had stabilizing effects on MT. The present results are discussed in relation to previous findings of inhibition of rapid axonal transport in vitro in the frog sciatic system by barbiturates.
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    Fine structure of the spermatheca of the mealworm beetle (Tenebrio molitor L.) (1975)
    Springer
    Cell & tissue research 162 (1975), S. 253-269 
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    ISSN: 1432-0878
    Keywords: Spermatheca ; Ultrastructure ; Cuticle ; Secretory cells ; Sperm storage ; Exocrine glands ; Insect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The spermatheca of the female mealworm beetle is an inflorescence of branching cuticular ducts which is connected to the bursa copulatrix via a cuticular neck surrounded by a muscular coat. The infolded bursal cuticle consists of a distinct outer epicuticle, inner epicuticle, procuticle, and a subcuticular zone; the latter is rich in mucopolysaccharides. The cuticle of the neck lacks a distinct procuticle. The cuticle of the spermatheca itself is mostly inner epicuticle with two thin underlying lamellae of procuticle. The cells of the bursa are loosely coupled to the procuticle, whereas cuticular projections bind the epithelia of the “neck” and the spermatheca proper to the underlying epithelia. The apical plasma membranes of the spermathecal epithelium are sinuous and much infolded; we believe that this epithelium controls the micro-environment within the cuticular ducts.
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    Ultrastructure of the larval corpus allatum of Hyphantria cunea drury (Insecta, Lepidoptera) (1975)
    Springer
    Cell & tissue research 162 (1975), S. 395-410 
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    ISSN: 1432-0878
    Keywords: Larval corpus allatum ; Activity cycles ; Lepidoptera ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The corpora allata of the three last larval instars were studied in newly molted animals, at the beginning, middle, and end of the feeding period, and during the molt period. They were found to consist of uniform gland cells, whose ultrastructure changes in the course of the instars. In gland cells considered to be resting, the outer and inner nuclear membranes run in parallel without forming a dilated perinuclear space. Mitochondria are small, polymorphic, with an electron-dense matrix. The smooth endoplasmic reticulum (SER) appears as stacks of parallel cisternae near the nuclear envelope and in the rest of the cytoplasm, and as accumulations of twisted profiles. Occasionally, the SER takes the form of paracrystalline bodies. There are few small smooth-surfaced vesicles in the cytoplasm. In cells considered as active, a dilated perinuclear space occurs. The peripheral ends of profiles forming the SER are swollen, and numerous vesicles and vacuoles bud off from them to fill the cytoplasm. Mitochondria are large, with a more transparent matrix. The plasma membrane of gland cells located just beneath the connective tissue sheath forms numerous small invaginations. The corpora allata consist of resting cells during the molt periods. At the beginning of each instar, few active gland cells appear. In the middle of the second to last and the third to last instars, the bulk of the gland cells is active. At the end of these instars, there are both active and inactive cells. In the middle of the last instar, the gland cells are inactive or subactive, and at its end, all gland cells are completely inactive.
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    The general ultrastructure of the carotid body of the domestic fowl (1975)
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    Cell & tissue research 162 (1975), S. 483-497 
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    ISSN: 1432-0878
    Keywords: Carotid body ; Domestic fowl ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic studies of the carotid body of the domestic fowl (Gallus gallus domesticus) have shown Type I and Type II cells combined with axons into compact groups. The many Type I cells in the depths of the organ had a body, containing the nucleus, and an elongated, flared process. Some of the Type I cells in the superficial regions tended to be spindle-shaped. Type I cells were characterised by membrane-bound, dense-cored vesicles about 120 nm in diameter. Type II cells invested the Type I cells and had axons embedded in them as in Schwann cells. The fine structure of the carotid body in the domestic fowl resembles that of the Lovebird (Uroloncha domestica) and of various amphibia and mammals. The possibility is discussed that the Type I cells may have a chemoreceptor or a general secretory function, or even both pathway for functions together. The main role of the Type II cells seems to be to provide a of these axons leading to or from Type I cells.
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    Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) (1975)
    Springer
    Cell & tissue research 164 (1975), S. 331-355 
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    ISSN: 1432-0878
    Keywords: Flight muscle ; Denervation ; Peripheral Wallerian degeneration ; Metamorphic axon degeneration ; Antheraea (Lepidoptera) ; Trophic action ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the moth Antheraea polyphemus the innervation of the anlage of the dorsolongitudinal flight muscle (dlm) was transected at the onset of adult development. The subsequent breakdown of the isolated motor stumps during early adult development was studied at the ultrastructural level. First reactions are seen on the second day of development when axonal mitochondria shrink. Later, elongated vesicles similar in structure to channels of smooth ER, appear in large numbers in the axoplasm. Their nature as well as the functional aspects of early axonal changes are discussed. From the 7th day onward two types of axonal breakdown become prominent. The first is characterized by swelling axon profiles, distorted vesicles and strongly shrunken mitochondria, while shrinking axon profiles containing tightly packed mitochondria and unaltered vesicles are typical of the second. Both types presumably take place independently of each other in different axon terminals. Axons and the contents of at least the first type are finally removed by transformation into lamellar bodies. Glial processes obviously behave independently of degenerating terminals; they loose any contact with them and never act as phagocytes for axon remnants. During the whole period of breakdown undifferentiated contacts between nerve fibers and muscle anlagen are present but synaptic structures as in normal developing dlm have never been observed. This fact, in comparison with earlier studies, suggests a lack of trophic nervous activity on the muscle anlagen tissue. A short time after removal of the isolated stumps new nerve tracts appear between dlm-fibers (which are, of course, strongly retarded in development). They are presumably sensory wing nerves which lack a guide structure to the central target, due to axotomy. Neuromuscular contacts or even junctions formed by axons of these nerves have occasionally been detected on the dlm. Their nature is discussed. Wallerian axon degeneration is compared to the normal, metamorphic breakdown of the innervation of the larval dlm-precursor. In contrast to the former, glial processes here remain in contact with the terminals. Glia and axons first swell. Then most glial processes are transformed into lamellar bodies whereas neuntes shrink and become electron-dense. Axonal organelles remain intact for a long period.
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    Electron microscopic studies on the pineal organ of the antarctic penguin, (Pygoscelis papua) (1975)
    Springer
    Cell & tissue research 164 (1975), S. 559-570 
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    ISSN: 1432-0878
    Keywords: Pineal organ ; Antarctic birds ; Penguin (Pygoscelis papua) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal organ of the migratory antarctic penguin, Pygoscelis papua, has a lobular structure. Clusters formed by different types of parenchymal cells are separated by connective tissue septa containing blood vessels. The predominant cell type displays a well-developed Golgi complex, free ribosomes, clear and granular vesicles (secretory granules), and lysosomes. Other cell types found in the gland are supporting and ependymal-like cells. The former contain dense bodies and filament bundles, the latter possess abundant cilia and clusters of ribosomes. Typical photoreceptor elements are lacking. Blood vessels are located within a perivascular space bordered by basal laminae. This perivascular space extends between the basal protrusions of the parenchymal cells. The presence of pinocytotic vesicles, secretory granules and cytoplasmic processes in the vicinity of these spaces suggests active sites of transport and exchange of substances. Intercellular canaliculi-like spaces are surrounded by parenchymal cells rich in microvilli. These canaliculi are continuous with the cavities (invaginations) of secretory and other parenchymal cells.
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    Stimulation of the adrenal gland of the mongolian gerbil after ovariectomy (1975)
    Springer
    Cell & tissue research 165 (1975), S. 135-139 
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    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Gerbils ; Castration ; Steroids ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of ovariectomy on the adrenal gland was studied in the Mongolian gerbil. Castration stimulated cells in the zona fasciculata as well as those in the region between the zona fasciculata and zona reticularis. No alterations occurred in the zona reticularis. The width of the intermediate region was enlarged, the cells were hypertrophic and contained an increased number of concentric whorls of rough endoplasmic reticulum. Smooth endoplasmic reticulum was hypertrophie in cells of the zona fasciculata and intermediate region. Many mitochondria in cells of the intermediate region were larger than those in controls. Stimulation of cellular ultrastructure is directly correlated with a significant elevation in plasma cortisol in ovariectomized gerbils.
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    Water regulation in aestivating snails (1976)
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    Cell & tissue research 173 (1976), S. 417-421 
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    ISSN: 1432-0878
    Keywords: Snails ; Water regulation ; Ultrastructure ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Aestivating snails form abundant lamellate vesicles in the cells of the mantle collar, an epithelium known to regulate the rate at which water is lost from its surface. Since lamellate vesicles are much reduced in hydrated mantle tissue of recently stimulated animals it is tentatively concluded that the vesicles, and their contents, form a barrier to water movement within these cells. X-ray microanalysis of unfixed thin sections shows that there is a concentration gradient of ions within these cells in aestivating animals which is not present in stimulated snails.
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    Studies on the ovotestis of the slug Agriolimax reticulatus (Müller) (1976)
    Springer
    Cell & tissue research 173 (1976), S. 465-482 
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    ISSN: 1432-0878
    Keywords: Ultrastructure ; Cytochemistry ; Oocytes ; Molluscs ; Vitellogenesis ; Nucleoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovarian oocytes of Agriolimax reticulatus (Müller) have been studied by light and electron microscopy and electron cytochemistry. The development of the oocyte in the ovotestis may be divided into three stages. During Stage I the oocyte cytoplasm contains mainly ribosomes and also strands of endoplasmic reticulum, scattered mitochondria and Golgi systems. The nucleus contains both a paranucleolus and an eunucleolus. By Stage II the oocyte has enlarged, especially in a plane parallel to the basement membrane. In addition to the above mentioned organelles, the cytoplasm contains lipid, glycogen and early yolk platelets. During Stage III, the oocyte continues to enlarge, but mainly in a plane perpendicular to the basement membrane. A considerable degree of cytoplasmic differentiation has also taken place. The plasma membrane of the oocyte has become specialized with the appearance of a polysaccharide-rich glycocalyx, microvilli and pinocytotic tubules. Elsewhere, much of the background cytoplasm, containing Golgi-derived, polysaccharide and acid phosphatase-rich multivesiculate bodies, lipid and glycogen, is sequestered by smooth membranes and ultimately fuses with the growing yolk platelets. The nucleus contains an amphinucleolus, characteristic of many gastropods. The findings of this study are discussed in relation to results from other studies on oogenesis.
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    Cytophysiology and innervation of gonadotropic cells in the pituitary of the Black Molly (Poecilia latipinna) (1976)
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    Cell & tissue research 174 (1976), S. 35-54 
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    ISSN: 1432-0878
    Keywords: Pituitary ; Teleost ; GTH-cells ; Innervation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the male black molly, Poecilia latipinna, morphological and functional aspects of the gonadotropic (GTH-)cells have been studied at the ultrastructural level. The cells exclusively occupy the ventral and lateral areas of the meso-adenohypophysis. In the black molly there is evidence of the presence of only one type of gonadotropic cell. In the GTH-cells of most specimens, the rough endoplasmic reticulum is weakly developed. The secretory vesicles are characterized by cores with varying diameters; this variation was not observed in the secretory vesicles of the other types of pituitary cells, except in the TSH-cells. After applying a histochemical method for the demonstration of polysaccharides, small black deposits appear in the core of the secretory vesicles of the GTH and TSH-cells only; this indicates the glycoproteinaceous nature of the hormones produced in these cells. Male black mollies treated with methyl-testosterone have significantly smaller GTH-cells and a lesser number of secretory vesicles and mitochondria in these cells. GTH-cell activity in Poeciliinae may be thus influenced by androgens by means of a negative feed-back mechanism. The GTH-cells are innervated by both type A and type B neurosecretory fibres. There are indications that the type A fibres may originate from the pars lateralis cells of the nucleus lateralis tuberis; the origin of the type B fibres is uncertain.
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    The relation between cell proliferation, differentiation and ultrastructural development in rat intestinal epithelium (1976)
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    Cell & tissue research 174 (1976), S. 183-199 
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    ISSN: 1432-0878
    Keywords: Rat small intestine ; Differentiation ; Ultrastructure ; Morphometry ; X-irradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural development of the principal cells in rat small intestine was studied by morphometric analyses in relation to the exact cell position along crypt and villus. From the bottom to the tip of the crypt, a gradual increase occurred in absolute size of the total cell, the cytoplasm, the terminal web and of nearly all cell organelles. Also, the relative size of the cytoplasm, mitochondria, microvilli and endoplasmic reticulum increased during crypt cell differentiation. No sudden changes in ultrastructure were observed in the so-called “critical decision zone”, normally located halfway up the crypt where the proliferative activity ceases. At the crypt-villous junction a 1.4–3 fold increase in cell size, cytoplasm, terminal web and of most organelles was noted. Expansion of the proliferative cell compartment over the total length of the crypt as occurs during recovery after a low X-irradiation dose (72 h after 400 R) does not affect the normal development of cellular ultrastructure. These findings are discussed in relation to biochemical and cell kinetic data.
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    Perivascular regions of the rat neural lobe (1976)
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    Cell & tissue research 174 (1976), S. 273-280 
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    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Ultrastructure ; Perivascular space ; Tannic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neural lobes and portions of occipital cortex from rats were examined electron microscopically following fixation in 4% tannic acid in 2.5% glutaraldehyde. The procedure allowed a clear demonstration of the perivascular space and intercellular spaces in both tissues. The perivascular spaces in the neurosecretory tissue was far more extensive than in the neural tissue and the role of this region in relation to the process of neurosecretion is discussed.
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    Organ culture of adult Rat and mouse tracheal epithelium: I. Ultrastructure following various culture periods (1976)
    Springer
    Cell & tissue research 165 (1976), S. 371-382 
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    ISSN: 1432-0878
    Keywords: Tracheal epithelium, Organ culture ; Rat, mouse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic studies of adult rat and mouse tracheal epithelium maintained in organ culture for a period of up to 6 days were performed. In specimens cultured for 60 minutes no conspicuous micromorphological alterations could be observed. Following culture periods from 1–6 days the number of cilia in some of the ciliated cells was reduced while their structure and the other ultrastructural details of the epithelial cells were preserved. In specimens cultured for 5–6 days some additional alterations could be noticed: polymorphism of mitochondria, increased number of lysosomes, appearance of intracellular vacuoles, exhaustion of goblet cells and disappearance of granulated mast-cell like cells in the rat tracheal epithelium. I want to thank Miss J. Selbmann and Mrs. S. Kolassa for technical help and Mr. H. Wagner for preparing the micrographs; I am indebted to Dr. D. Kerjaschki and to Mr. H. Hörandner for performing preparations for scanning electron microscopy and to Mr. P. Scholze (Österreichische Studiengesellschaft für Atomenergie, Institut für Metallurgie, Abteilung Fremdkörperphysik) for preparing the scanning electron micrograph.
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    URL: http://dx.doi.org/10.1007/BF00222440
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    The fine structure of the hypothalamic secretory neurons of the White-crowned Sparrow, Zonotrichia leucophrys gambelii (Passeriformes: Fringillidae) (1976)
    Springer
    Cell & tissue research 165 (1976), S. 415-434 
    Details
    ISSN: 1432-0878
    Keywords: Rostral hypothalamus ; Secretory neurons ; Magnocellular and parvocellular systems ; Ultrastructure ; Zonotrichia leucophrys gambelii (Aves)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structures of the neurons and neuropils of the magnocellular supraoptic nucleus and the parvocellular nuclei of the rostral hypothalamus, including the suprachiasmatic and medial, lateral and periventricular preoptic nuclei, and the neuronal apparatus of the organum vasculosum laminae terminalis, have been examined in the male White-crowned Sparrow, Zonotrichia leucophrys gambelii, by correlated light and electron microscopy. The magnocellular supraoptic nucleus is characterized by large neurosecretory perikarya which contain a well developed Golgi complex and densecored granules 1,500–2,200 Å in diameter. The neuropil displays axons, dendrites and glial fibers. Some axonal profiles contain dense-cored vesicles 800–1,000 Å in diameter and clear vesicles 500 Å in diameter. Axo-somatic and axo-dendritic synapses are conspicuous in this nuclear region. The suprachiasmatic nucleus is characterized by an accumulation of small neurons with moderately developed cellular organelles and some dense-cored granules, approximately 1,000 Å in diameter. The profiles of axons within the neuropil contain dense-cored granules 800–1,000 Å in diameter and clear vesicles 500 Å in diameter. The neurons of the medial preoptic nucleus are relatively large and exhibit well developed cellular organelles and dense-cored granules 1,300 to 1,500 Å in diameter. Granular materials are formed within the Golgi complex. The medial preoptic nucleus is rich in secretory perikarya. Occasionally, neurons with granules 1,500–2,200 Å in diameter are encountered in the lateral preoptic and periventricular preoptic nuclei. They may be considered as scattered elements of the magnocellular (supraoptic and paraventricular) system. The organum vasculosum laminae terminalis consists of three layers, i.e., ependymal, internal and external zones, and exhibits a vascular arrangement similar to that of the median eminence. The perikarya of the parvocellular neurons and their axons in the internal zone contain numerous secretory granules ranging from 1,300 to 1,500 Å in diameter.
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    The effects of prostaglandin F2α on the fine structure of the corpus luteum of the pregnant hamster (1976)
    Springer
    Cell & tissue research 174 (1976), S. 465-474 
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    ISSN: 1432-0878
    Keywords: Prostaglandin ; Ultrastructure ; Corpus luteum ; Pregnancy ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Corpora lutea (C.L.) from normal and prostaglandin-treated pregnant hamsters were examined by light and electron microscopy. Luteal cells from pregnant control animals were hypertrophied and contained an abundance of agranular endoplasmic reticulum (AER) suggesting steroidogenic activity. Animals which were injected on day 4 of pregnancy had ovulated by the third day following the injection, hence, two generations of corpora lutea were present in the ovary. Luteal cells from the “old” C.L. of pregnancy underwent a progressive degeneration during the four days following the single prostaglandin injection, whereas, cells from “new” C.L. appeared viable in most respects. The presence of aggregated platelets in both “old” and “new” C.L. was noted. It is suggested that the “new” C.L. are responsible for the rebound of plasma progesterone reported in previous investigations three days following prostaglandin treatment in pregnant hamsters.
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    URL: http://dx.doi.org/10.1007/BF00232833
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    Ultrastructural diversity in motor units of crustacean stomach muscles (1976)
    Springer
    Cell & tissue research 166 (1976), S. 159-166 
    Details
    ISSN: 1432-0878
    Keywords: Muscle ; Stomach ; Crab ; Physiology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The physiological and ultrastructural properties of muscle fibers comprising three motor units in the gastric mill of blue crabs are described. In their contractile properties muscle fibers in all motor units are similar and resemble the slow type fibers in crustacean limb muscles. The majority of fibers generate large excitatory post-synaptic potentials which do not facilitate strongly. Structurally two types of fibers are found. The one type has long sarcomeres (〉6 μm), thin to thick myofilament ratios of 5–6∶1 and diads located near the ends of the A-band. The other type has shorter sarcomeres (〈 6 μm), thin to thick myofilament ratios of 3∶1 and diads located at mid sarcomere level. Both types of fibers occur within a single motor unit and this differs from the vertebrate situation. Furthermore, the finding of fibers with a low thin to thick myofilament ratio of 3∶1 demonstrates that they are not exclusive to fast type crustacean muscle but also occur in slow stomach muscles.
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    URL: http://dx.doi.org/10.1007/BF00227037
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  • 41
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    Effects of chronic exercise on the ultrastructure of the adrenocortical cells in the rat (1976)
    Springer
    Cell & tissue research 168 (1976), S. 261-270 
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    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Exercise ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Four groups of male rats were exercised for periods of 2, 4, 6, and 8 weeks with controls in each group. As a result of chronic exercise there was an increase in the width of the zona fasciculata of the adrenal cortex. Also, there was an increase in the number and size of the mitochondria, and an increase in the quantity of smooth endoplasmic reticulum, and during the first 4 weeks of exercise an increase in the number of lipid droplets in the zona fasciculata. The close relationship between the smooth endoplasmic reticulum and the mitochondria, and the relationship between the smooth endoplasmic reticulum and the lipid droplets suggests a possible means for a transport mechanism for movement of precursors between these organelles.
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    URL: http://dx.doi.org/10.1007/BF00215882
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  • 42
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    Neurosecretion in the basommatophoran snail Bulinus truncatus (Gastropoda, Pulmonata) (1977)
    Springer
    Cell & tissue research 176 (1977), S. 57-67 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Alcian blue ; Alcian yellow staining ; Ultrastructure ; Bulinus truncatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurosecretory system of the freshwater snail Bulinus truncatus was investigated. With the Alcian blue-Alcian yellow (AB/AY) staining method at least 10 different types of neurosecretory cells (NSC) were distinguished in the ganglia of the central nervous system. The differences in staining properties of the NSC — with AB/AY the cells take on different shades of green and yellow — are borne out at the ultrastructural level: the NSC types contain different types of neurosecretory elementary granules. The neurosecretory system of B. truncatus is compared to that of Lymnaea stagnalis, the species which has received the most attention among the pulmonates. It appears from the comparison that the systems of both species show many similarities, although some differences are also apparent.
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    URL: http://dx.doi.org/10.1007/BF00220344
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    Cytological evidence for different types of cerebrospinal fluid-contacting subependymal cells in the preoptic and infundibular recesses of the frog (1977)
    Springer
    Cell & tissue research 176 (1977), S. 317-334 
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    ISSN: 1432-0878
    Keywords: CSF-contacting subependymal cells ; Frog hypothalamus ; Fluorescence microscopy ; Autoradiography ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Blue-green fluorescent subependymal cells with intraventricular processes were shown by the fluorescent histochemical method to be distributed from the preoptic recess to the infundibular recess of the frog hypothalamus. Electron microscopy revealed at least two types of CSF-contacting subependymal cells, type 1 containing large dense granules (about 100–200 nm in diameter) and type 2 containing small dense core vesicles (about 60–100 nm in diameter). Subsequent to fixation in permanganate solution, the small dense core vesicles in type 2 cells reacted with the fixative and consistently showed a dense content. However, the large granules in type 1 cells were mostly pale or less dense after this fixation. Two hours after intraventricular injection of 3H-dopamine, a large number of silver grains appeared only in the cytoplasm of intraventricular processes possessing dense core vesicles (type 2 cells). A few grains were also found in the perikarya. It is concluded that type 2 cells are catecholamine-storing cells. It is suggested that type 1 cells in the infundibular recess are peptidergic neurons which may secrete some hypothalamic regulating hormones of the anterior pituitary. Most of these cells in the preoptic recess belong to the neurosecretory cells of the preoptic nucleus, while some cells probably function similarly to those in the infundibular recess.
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    URL: http://dx.doi.org/10.1007/BF00221791
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    Ultrastructure of nerve plexus in flatworms (1977)
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    Cell & tissue research 176 (1977), S. 335-347 
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    ISSN: 1432-0878
    Keywords: Flatworm ; Nerve-net ; Epithelium ; Ultrastructure ; Synapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In addition to a submuscular and subepithelial nerve plexus an infra-epithelial nerve-net also occurs in Notoplana acticola. It contains naked nerve cells which lie between the bases of epithelial cells. Individual neurites occur separately or in small tracts. Synapses contain clear spherical vesicles and are polarized. Post-synaptic neurites tend to be flat and ribbon-like. Rhabdite and mucus secreting cells in the epithelium have synapses associated with them. Neurites ending on the rhabdites appear to originate in the subepithelial plexus. The “sensory-free nerve endings” of earlier workers are reinterpreted as being motor terminals on epithelial secretory cells.
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    URL: http://dx.doi.org/10.1007/BF00221792
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    Ultrastructure of the rat pineal gland grafted under the kidney capsule (1977)
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    Cell & tissue research 176 (1977), S. 131-142 
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    ISSN: 1432-0878
    Keywords: Pineal gland ; Graft ; Ultrastructure ; Innervation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pineal glands were grafted under the kidney capsule of mature male rats for periods of 20, 40, 60 and 100 days. Each grafted gland was then excised and divided into two halves. One half was processed for conventional electron microscopy and the other was fixed in aldehydes and then incubated in a zinc iodide-osmium tetroxide mixture at pH 4.4 (A-ZIO-4.4). During the forty days following the operation pinealocytes showed the typical ultrastructural features associated with cells with a high protein and/or peptide secretory activity. On the other hand, during this period, the number of granular vesicles decreased progressively. From day 40 on, the grafted pinealocytes lacked granular vesicles. During the second half of the experimental period the ultrastructure of the pinealocytes indicated that their secretory activity was considerably decreased. During the acute phase of the experimental period numerous structures regarded as the tip of growing axons as well as typical nerve fibres appeared around blood vessels and within the parenchyma of the grafted gland. In the transplanted tissue obtained 60 and 100 days after the operation the growth cones were scarce, whereas typical nerve endings became numerous. These endings contained small clear vesicles which reacted positively when the tissue was treated with A-ZIO-4.4. The secretory activity of the grafted pineal gland and the nature of the nerve fibres which innervate the graft are discussed. The authors wish to thank Mrs. E.M. Rodríguez de Calderón for her valuable help
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    The fine structure of the compound eye of Squilla mantis (crustacea, stomatopoda) (1977)
    Springer
    Cell & tissue research 176 (1977), S. 205-233 
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    ISSN: 1432-0878
    Keywords: Eye ; Retina ; Squilla mantis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the compound eye of adult specimens of Squilla mantis was investigated. The eye consists of about 3600–3700 ommatidia, each containing a dioptric apparatus formed by a lamellated corneal lens and a eucone-type crystalline cone. Each of the four cone cells give rise to a cylindrical process (crystalline thread) inserted between the retinula cells and extending down to the basement membrane. Two distal pigment cells completely encompass the distal part of the crystalline cone, becoming progressively smaller and forming roundish processes. At the level of the tip of the crystalline cone they split off into small pigment-containing processes, and a central process leads down to the basement membrane. About 12–16 proximal pigment cells surround the ommatidium and extend from the tip of the crystalline cone to the basement membrane. In addition to the two types of pigment cell, three other types of pigment-containing cells were identified, one of which possibly contains — on the basis of their ultrastructure — crystals of the respiratory pigment hemocyanin. The two other pigments are found respectively on the surface of the retina (green pigment) and beneath the surface and in the intraommatidial space (white pigment). The distal part of each ommatidium consists of retinula cells of about equal size. Further proximal an 8th small retinula cell is encountered. The fused, centrally located rhabdom, is built up of the microvilli (rhabdomeres) of the 7 large retinula cells, the 8th has no microvilli. The structure of the ommatidia was also examined in relation to light-dark adapted conditions (LA-DA). In DA the crystalline cone shortens and the rhabdom becomes longer by an approximately corresponding amount and the pigments of the distal pigment cells expand more distally. The number and type of special cytoplasmic inclusions, as well as the shape and size of the socalled perirhabdomal vacuoles, seems not to be changed by light or dark-adaptation. In the 7 large retinula cells, an unusual migration of pigment granules occurs under DA conditions (the 8th does not contain pigment granules). In DA, many of granules which are distributed around the rhabdom in LA, line up in rows, like strings of pearls, along the rhabdom, forming a dense pigment coat around it. The findings are compared with those of related studies and their functional implications for the vision of Squilla are discussed.
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    Fine structure of the corpus luteum of pregnancy in the gerbil (Meriones unguiculatus) (1977)
    Springer
    Cell & tissue research 176 (1977), S. 361-371 
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    ISSN: 1432-0878
    Keywords: Corpus luteum ; Gerbil (Meriones) ; Pregnancy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Corpora lutea from gerbils on days 1, 4, 8, 12, 16, 20 and 24 of pregnancy were studied electron microscopically. Similarly, luteal tissue from animals on the day of parturition and one day postpartum was studied (gestation: 24 days ± 8–24h). Agranular endoplasmic reticulum increases in quantity through day 16 and thereafter is somewhat reduced. Granular endoplasmic reticulum and a population of small granules (type I) become abundant during late pregnancy and their possible role in the production and storage of relaxin is discussed. Luteal tissue undergoes a relatively rapid regression which begins on the day of parturition. Conspicuous in the regressing luteal tissue are large (type II) granules (possibly lysosomes), lipid droplets, leucocytic elements and macrophages. Functional correlates of these morphological findings are discussed.
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    Comparative ultrastructural study of the effects of serum-free medium and dibutyryl-cyclic AMP on newborn rat astroblasts (1976)
    Springer
    Cell & tissue research 167 (1976), S. 221-227 
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    ISSN: 1432-0878
    Keywords: Glial Cells ; Cyclic AMP ; Differentiation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Modifications of cell shape induced in cultured newborn rat astroblasts by serum deprivation or dibutyryladenosine 3′–5′ monophosphate (dBcAMP) are described. Serum suppression modifies the adhesivity of the cells to the substrate, but this modification is not consistent with a true differentiation. The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 Å microfilaments, while control cells are relatively devoid of these structures.
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    Comparative ultrastructural investigations of the pineal organ of the blind cave fish, Anoptichthys jordani, and its ancestor, the eyed river fish, Astyanax mexicanus (1976)
    Springer
    Cell & tissue research 167 (1976), S. 297-324 
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    ISSN: 1432-0878
    Keywords: Pineal organ ; Blind cave fish ; Astyanax mexicanus ; Regressive evolution ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A comparative ultrastructural study has been made of the pineal organ in specimens of two closely related populations of the characid fish, Astyanax mexicanus. The specimens of one population are living in the river, under natural light conditions. The specimens of the other population, originally described as Anoptichthys jordani, are living in a completely dark cave. In specimens of both populations the pineal organ consists of a spindle shaped end-vesicle, connected to the diencephalic roof by a slender stalk. The pineal tissue is compact and consists predominantly of glia-like supporting cells and sensory cells resembling the photoreceptor cells of the lateral vertebrate eye. Phagocytotic microglia-like cells can be found in close contact with the outer segments of the sensory cells. Nerve cells are located in the neighbourhood of neuropil formations, in which synaptic contacts are established between sensory cells and nerve cells. From these nerve cells fibers are emerging, forming the pineal tract that runs down the pineal stalk towards the diencephalon. On the basis of the ultrastructure described by other authors it is concluded that the pineal organ in specimens of the river population of Astyanax mexicanus resembles the pineal organ of other fish species. In specimens of the river population, reared under normal light-dark conditions for 3, 9 or 18 months, conspicuous morphological changes have not been detected in the presumably light-sensitive outer segments of the sensory cells or in other parts of the pineal tissue. In specimens of the cave populations, reared under identical conditions, an age-dependent, gradual regression of the regular outer segment organization of the pineal sensory cells takes place. In other parts of the pineal tissue, only small morphological changes can be observed. In specimens of the cave population, reared in constant darkness, the regression of the pineal outer segment organization begins earlier and is obvious. It is postulated that the gradual age-dependent regression of the regular organization of the outer segments in the pineal organ of cave specimens of Astyanax mexicanus is genetically determined and indicates a regressive evolution of the pineal light sensitivity. The expression of the regressive traits is dependent on the environmental light conditions.
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    URL: http://dx.doi.org/10.1007/BF00219144
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    The effects of testosterone, 5α-dihydrotestosterone, 3α-androstanediol, and 3β-androstanediol on epithelial fine structure of the rabbit epididymis in organ culture (1976)
    Springer
    Cell & tissue research 167 (1976), S. 493-514 
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    ISSN: 1432-0878
    Keywords: Epididymis ; Rabbit ; Organ culture ; Androgens ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the corpus epididymidis of the rabbit has been studied following organ culture. Various modifications of tissue preparation and culture conditions were examined to obtain good maintenance of cellular integrity as well as to preserve sperm fertilizing ability. After 5 to 7 days in culture in the absence of hormonal support, the epididymal epithelium showed signs indicative of cellular regression. Such changes included shrinkage of the cells, loss of the border of stereocilia, decrease in smooth endoplasmic reticulum, and an increase in autophagic vacuoles. The presence of androgens in culture media prevented cellular regression to varying degrees, depending on the hormone utilized. With regard to maintenance of cellular integrity, potency of the androgens tested was as follows: 5α-dihydrotestosterone 〉= 3α-androstanediol 〉 testosterone 〉 3β-androstanediol. Addition of insulin to dihydrotestosterone-containing cultures resulted in no improvement in maintenance. Phagocytosis of spermatozoa by epithelial cells was observed in cultured tubules and the degree of spermiophagy was inversely proportional to successful maintenance of fine structural characteristics of epithelial cells. The morphological findings reported here correlate well with the fertilizing ability of spermatozoa from cultured epididymis as reported in an accompanying communication.
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    The lateral photoreceptor of the barnacle, Balanus eburneus (1976)
    Springer
    Cell & tissue research 168 (1976), S. 193-207 
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    ISSN: 1432-0878
    Keywords: Lateral eye ; Barnacle ; Morphometry ; Osmium fixation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lateral eye of the barnacle, Balanus eburneus, fixed in highly concentrated osmium is a lens-shaped body of approximately 250 μm in diameter and about 75 μm thick. It contains three photoreceptor cells which occupy about 42% of its volume. The photoreceptor cells are irregularly shaped and extend countless dendritic processes which bear rhabdomeres at their ends. Individual rhabdomeres come into contact with rhabdomeres originating from dendrites of the same or of one of the other visual cells. Thirteen per cent of the volume of the photoreceptor cells is taken up by the rhabdomeres. The membranes of the rhabdomeric microvilli contain globular subunits which suggest a 70 Å spacing of rhodopsin molecules. There are two kinds of glial cells. One kind, type A glial cells, makes contact with the fibrous capsule of the photoreceptor. The other kind, type B glial cells, is associated with the photoreceptor cells and extends countless tiny cytoplasmic extensions which interdigitate with similar extensions of the receptor cells. There are approximately 95 type B glial cells and 130 type A glial cells in the receptor. The cytoplasm of the photoreceptor cells contains countless small Golgi fields, mitochondria, microtubules, multivesicular and multilamellar bodies. The extracellular space of the photoreceptor is less than 0.1% of its total volume.
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    The villous stroma of the human placenta (1977)
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    Cell & tissue research 177 (1977), S. 105-121 
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    ISSN: 1432-0878
    Keywords: Human placenta ; Villous stroma ; Fixed stromal cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In human placental villi the connective tissue is constructed by mesenchymal cells, small and large reticulum cells and fibroblasts. During early pregnancy mesenchymal cells dominate; starting with the third month of gestation the reticulum cells are in the majority within the terminal villi, the fibroblasts within the stem villi. Ultrastructurally intermediary types of cells can be differentiated. Together with reticular and collagenous fibres the reticulum cells form the basic architecture of the villous stroma during the first 2/3 of gestation: the “reticular type of stroma”. This consists of a network of cells and fibres with fetal vessels fitted in between. The remaining interspaces form a fluid system of compartments in which Hofbauer cells are suspended. They are called stromal channels. During the last trimester these channels and the Hofbauer cells as well are progressively replaced either by voluminous masses of fibres (“fibrous type of stroma”, mainly in the stem villi) or by sinusoidal enlargements of fetal capillaries (“sinusoidal type of stroma”, mainly in the terminal villi).
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    The accessory outer segment of rods and cones in the retina of the guppy, Poecilia reticulata P. (teleostei) (1977)
    Springer
    Cell & tissue research 177 (1977), S. 181-193 
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    ISSN: 1432-0878
    Keywords: Accessory outer segment ; Photoreceptors ; Poecilia reticulata P. ; Ultrastructure ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the accessory outer segment (AOS) — a ciliumlike structure emanating from the inner segment and running alongside the outer segment of photoreceptors — is described. The AOS occurs in both rods and cones of Poecilia reticulata. Its ultrastructure, including the arrangement of microtubules, which originate from the ciliary stalk, is the same in rods and cones. The cone-AOS is connected with the outer segment by a thin plasmabridge, whereas the rod-AOS lies embedded within the outer segment. The outer segment of the cone, in contrast to that of the rod, is separated from the pigment epithelium by a large extracellular space. An intimate contact, however, is secured by the AOS; its membrane is closely appositioned to the pigment epithelium membrane. The functional significance of the AOS and its possible occurrence in other vertebrate classes, are discussed.
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    Ultrastructural changes in midgut cells of female Aedes aegypti L. (insecta, diptera) after starvation or sugar diet (1977)
    Springer
    Cell & tissue research 177 (1977), S. 215-219 
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    ISSN: 1432-0878
    Keywords: Aedes aegypti ; Midgut epithelium ; Ultrastructure ; Starvation ; Sugar diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Nach einer Hungerperiode von 5 bzw. 8 Tagen ist die Ultrastruktur der Epithelzellen im hinteren Abschnitt des Mitteldarmes weiblicher A. aegypti teilweise verändert. So wird beispielsweise eine drastische Reduktion des rauhen endoplasmischen Retikulum (rer) gemessen, das für die Synthese der Enzyme zur Blutverdauung verantwortlich ist. Einen ähnlichen Einfluß auf das rer hat eine gleich lang dauernde Fütterung der Mücken mit Zuckerwasser.
    Notes: Summary The ultrastructure of the epithelial cells in the posterior part of the midgut in female Aedes aegypti was partly changed after starvation periods of 5 or 8 days. Most obvious is a drastic reduction of the amount of rough endoplasmic reticulum (rer), which is responsible for the synthesis of enzymes for blood digestion. A similar influence on rer membranes is to be observed in mosquitoes fed on sucrose solution only, without additional blood meals.
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    The effect of age on the ultrastructure of the mid-gut cells of the hymenopteran Nasonia vitripennis (Walk.) (Hymenoptera, Pteromalidae) (1977)
    Springer
    Cell & tissue research 177 (1977), S. 239-245 
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    ISSN: 1432-0878
    Keywords: Insects ; Mid-gut ; Aging ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the mid-gut cells of aged female Nasonia vitripennis is described. The mid-gut is a shrunken and distorted organ in the aged animal. The individual cells are highly disorganised and the organelle components are altered. The small lipid droplets formed in the apical cell region do not coalesce to form the large central lipid inclusions characteristic of the young animal. The rough endoplasmic reticulum is reduced and some of the mitochondria enlarge. The mid- and apical cell regions also contain large numbers of cytolysosomes. The basal cell region is essentially unchanged, but the channels formed by the infolded basal plasma membranes are dilated. The changes observed are discussed in relation to previous observations on other insect species.
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    Ultrastructure of an excitatory synapse (1979)
    Springer
    Cell & tissue research 200 (1979), S. 291-298 
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    ISSN: 1432-0878
    Keywords: Excitatory synapse ; Lateral line-canal organ ; Synaptic body ; Ultrastructure ; Lota lota (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the afferent synapse in hair cells of the lateral line-canal organ was studied using different fixation and staining techniques. Glutaraldehyde-fixed tissue without post-osmication, contrasted by section staining with uranyl acetate and lead citrate, was compared with (a) osmium tetroxide-fixed tissue followed by the same staining procedure, and with (b) glutaraldehyde-fixed tissue, block-impregnated with phosphotungstic acid (PTA). The results reveal a pronounced heterogeneity in the composition of the synaptic body, reflecting regional differences in chemical affinity to the fixatives and staining agents. It is proposed that the “intracleft substance”, the synaptic structure defined by the PTA staining technique, is actually due to the glutaraldehyde fixation procedure and is apparently the outer leaflet of the postsynaptic membrane. A special technique that allows alternate sections of a series to be differentially stained for electron microscopy is proposed.
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    URL: http://dx.doi.org/10.1007/BF00236421
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    Fenestrated blood capillaries and lymphatic capillaries in rat skeletal muscle (1975)
    Springer
    Cell & tissue research 163 (1975), S. 169-174 
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    ISSN: 1432-0878
    Keywords: Muscles ; Blood supply ; Capillaries ; Lymphatic system ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Capillary fenestrae occur in one of about 60 cross-sectioned blood capillaries in normal adult rat skeletal muscles. The fenestrae occur singly or in groups. Fenestrated capillaries are found close to muscle fibers as well as in the perimysial and perineurial connective tissue. Small numbers of lymphatic capillaries are also present, mostly in the perimysial connective tissue.
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    URL: http://dx.doi.org/10.1007/BF00221724
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    Hypertrophy of intestinal smooth muscle (1975)
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    Cell & tissue research 163 (1975), S. 199-214 
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    ISSN: 1432-0878
    Keywords: Smooth muscle ; Intestine ; Hypertrophy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Proximal to an experimental stenosis of the small intestine of rats and guinea-pigs a remarkable hypertrophy of the muscle coat develops 3–5 weeks after the operation. There is no increase in the length of the intestine but an overall increase in volume of the muscularis externa up to 10 times. This increase is accounted for by an increase in size and in number (by mitosis) of smooth muscle cells of both the longitudinal and circular layers. Bundles of newly-formed smooth cells appear in the serosa and are circularly arranged. In the hypertrophic smooth muscle cells of the circular layer the ratio of surface to volume is 0.80 (0.80 μm2 of cell surface for every μm3 of cell volume) as against 1.4 in the control muscle. The hypertrophic muscle cells have a highly developed sarcoplasmic reticulum and show a large number of nexuses. The density of innervation (number of axons per given number of smooth muscle cells) is smaller than in controls. Few collagen fibrils are visible in the extracellular space.
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    Ultrastructure of the presumed ion-transporting cells in the gills of ammocoete lampreys, Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) (1975)
    Springer
    Cell & tissue research 163 (1975), S. 327-341 
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    ISSN: 1432-0878
    Keywords: Chloride cell ; Gill filaments ; Ultrastructure ; Ion transport ; Ammocoete ; Lampetra fluviatilis (L), Lampetra planeri (Bloch)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Mitochondria-rich cells were located in the interplatelet area of gill filaments from ammocoete Lampetra fluviatilis and L. planeri. The ultrastructure of this cell type differs from typical teleost ‘chloride cells’ by the absence of a tubular, smooth endoplasmic reticulum (SER). This difference is discussed in relation to the presumed functions of the cell and to the evolutionary histories of lampreys and teleosts. It is concluded that the mitochondria-rich cell is responsible for the active uptake of ions by the ammocoete gill.
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    Ultrastructural observations of growth hormone (STH) cells of anterior pituitary glands of partially hepatectomized rats (1975)
    Springer
    Cell & tissue research 163 (1975), S. 343-351 
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    ISSN: 1432-0878
    Keywords: Growth-hormone cell ; Anterior pituitary ; Hepatectomy, rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural changes in pituitary growth-hormone cells were observed in partially hepatectomized rats. The hepatectomies were carried out during the afternoon after 3 p.m. The animals were sacrificed by decapitation at midnight at intervals of 32, 80, and 104 hours after the operation. The principal changes in the growth-hormone cells of anterior pituitary glands of partially hepatectomized rats were: (1) increased numbers of secretory granules in exocytosis, (2) increased numbers of microtubules, and (3) enlargement of endoplasmic reticulum and occurrence of dilated cisternae of the endoplasmic reticula. Many growth-hormone cells contained a reduced number of secretory granules. Exocytosis of growth-hormone granules was more frequently observed in animals sacrificed at 32 hours after the operation than in those killed at 80 or 104 hours after surgery. The above results in which appearance of numerous microtubules and active secretory granule extrusion in the growth-hormone cells were observed after hepatectomy indicate that ultrastructure of growth-hormone cells and growth hormone secretion were markedly stimulated by the operation.
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    Ultrastructural evidence for the existence of steroid synthesizing cells in the ovary of the starfish, Asterias rubens (Echinodermata) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 275-279 
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    ISSN: 1432-0878
    Keywords: Steroid synthesizing cells ; Steroidogenesis ; Ovary ; Ultrastructure ; Echinodermata, Asterias rubens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of cells showing characteristic features of steroid producing cells in the ovaries of the starfish, Asterias rubens, is described. The correlation between the appearance of these cells and steroid biosynthesis in ovarian tissue of A. rubens is discussed. The importance of the discovery of these cells in view of the biosynthesis of steroids and the phylogeny of Echinodermata is mentioned.
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    Morphological alterations and functional changes of interhepatocellular junctions induced by bile duct ligation (1977)
    Springer
    Cell & tissue research 182 (1977), S. 299-310 
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    ISSN: 1432-0878
    Keywords: Liver ; Bile duct ligation (rat) ; Cell membrane ; Intercellular junctions ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of bile duct ligation on the intercellular junctions of hepatocytes was investigated. The features and the arrangement of the bile canaliculi and the zonulae occludentes alter concomitant to the increase of the intracanalicular pressure. The lumen of the bile canaliculi enlarges and the microvilli disappear. The array of the zonulae occludentes becomes irregularly shaped, the number of strands diminishes and interruptions of the strands occur. With peroxidase a leakage in the bile-blood barrier is detected. Furthermore a disappearance of gap junctions between the hepatocytes after bile duct ligation is observed. The present investigation shows that the zonulae occludentes are mobile structures which are changed by increased unilateral pressure. Due to their ultrastructural alterations, a leakage of the permeability barrier between physiological compartments is found. We acknowledge the helpful criticism and discussion of Prof. H.D. Fahimi. We are indebted to Mrs. B. Brühl, M. Bürkle and Ch. Walenta for technical assistance, and to stud. med. Jon Greenberg for preparing the manuscript
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    Electron microscopic study of the mandibular glands of Kalotermes flavicollis Fabr. (Isoptera; Calotermitidae) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 327-339 
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    ISSN: 1432-0878
    Keywords: Ultrastructure ; Mandibular glands ; Kalotermes ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les glandes mandibulaires de Calotermes sont étudiées dans les différentes castes. Elles présentent un dimorphisme sexuel chez les soldats et les sexués. Après la mue imaginale, les cellules glandulaires ont toujours une activité sécrétrice. De plus, chez les soldats femelles et les reines, elles contiennent de nombreuses formations cristallines d'origine mitochondriale. Le rôle de ces glandes (sécrétion de salive ou de phéromone) est discuté.
    Notes: Summary The mandibular glands of Kalotermes were examined in different castes. They showed sexual dimorphism in the soldiers and primary reproductives. Moreover, in female soldiers and queens, mandibular gland cells contained numerous crystalline structures of mitochondrial origin. The role of these glands (secretion of saliva or pheromone) is discussed.
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    Fine structure of capillaries in the conus papillaris of the limbless lizard, Ophisaurus apodus (Anguidae, Lacertilia) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 421-424 
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    ISSN: 1432-0878
    Keywords: Lizard ; Eye ; Conus papillaris ; Capillaries ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The conus papillaris of Ophisaurus apodus consists of blood vessels and pigment cells. The capillary walls are formed by endothelial cells, scarce pericytes and basal laminae. The cell bodies are attenuated and the plasmalemma of their luminal and abluminal surfaces forms microvilli. The perivascular space is well developed, containing nerve fibers and their terminals. Similar localization and ultrastructure of avian pecten oculi and lacertilian conus papillaris suggest homology of these structures.
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    The neurosecretory cells of the optic lobe in Carcinus maenas (L) (1975)
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    Cell & tissue research 156 (1975), S. 403-409 
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    ISSN: 1432-0878
    Keywords: Neurosecretory cells ; Eyestalk ; Carcinus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The six types of neurosecretory cell in the optic lobe of Carcinus maenas described by light microscopy are recognised by electron microscopy. They are categorised according to size, distribution of organelles and type of neurosecretory product. The neuro secretory material, produced as granules by the Golgi bodies, migrates to the cell periphery eventually reaching the sinus gland via the neurosecretory cell axon extension. No change in size occurs in the granules but the density does alter. Each cell type has its own characteristic type of neurosecretory granule based on size and electron density. Multivesicular and lytic bodies in cell types 1, 2, 3,4 and 6 suggest a cycle for degrading neurosecretory material. Such a cycle is not so evident in cell type 5. Peripheral release of neurosecretory material is suggested for cell type 6 although the fate of the material is unknown.
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    Ultrastructural characterization by ruthenium red of the surface of the fat globule membrane of human and rat milk with data on carbohydrates of fractions of rat milk (1975)
    Springer
    Cell & tissue research 157 (1975), S. 17-24 
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    ISSN: 1432-0878
    Keywords: Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
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    The fine structure and phosphatase cytochemistry of the Golgi complex and associated structures in the Sertoli cells of Syrian hamsters (1975)
    Springer
    Cell & tissue research 157 (1975), S. 227-238 
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    ISSN: 1432-0878
    Keywords: Golgi complex ; GERL ; Sertoli cell ; Ultrastructure ; Phosphatase cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Golgi complex in the Sertoli cell of the Syrian hamster is well developed and consists of stacks of cisternae and associated vesicles. The inner-and outermost cisternae of the Golgi stacks are usually moderately dilated and exhibit numerous fenestrations. The middle portions of the intermediate cisternae are greatly flattened and not fenestrated, but toward the periphery these cisternae gradually become dilated and show a few fenestrations. On the inner aspect of the Golgi stacks the following structures are seen frequently: (1) one or two series of linearly arrayed circular profiles some of which are interconnected by tubules; (2) networks of anastomosing tubules with circular or oval meshes (800 to 1200 Å in diameter); and/or (3) irregularly disposed tubules. The circular profiles and tubules are approximately 450 Å in diameter. Acid phosphatase activity was localized in these anastomosing tubules when the tissues were incubated for more than one hour in a modified Gomori's medium (Barka and Anderson, 1963). Strong thiamine pyrophosphatase activity was demonstrated in the inner one to three cisternae of the Golgi stacks but not in the associated tubules. The system of the Golgi associated tubules is morphologically and histochemioally distinct from the Golgi stacks and is probably equivalent to the Golgi-endoplasmic reticulum-lysosome system (GERL) in other cell types. The three dimensional aspects of the GERL-equivalent system are discussed.
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    Interdigitating reticulum cells in the popliteal lymph node of the rat (1976)
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    Cell & tissue research 170 (1976), S. 43-60 
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    ISSN: 1432-0878
    Keywords: Interdigitating cells ; Lymph node ; Rat ; Ultrastructure ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electronmicroscopic and cytochemical studies were performed to localize interdigitating reticulum cells (IDC) in the popliteal lymph node of the rat. The morphological features of the IDC of the rat correspond to those described for other species, but also show similarities to normal macrophages in the rat. This is considered to be an argument in favour of the common origin of IDC's and macrophages. Ultrahistochemical studies with horseradish peroxidase (HRP) reveal no phagocytotic capacity of IDC's. After perfusion fixation containing ruthenium red (RR) the surface coat stains heavily: RR is also found deep in the membrane invaginations of the IDC, indicating the presence of polyanionic sialoglyco-proteins. The post-capillary-venules (PVC) are very permeable to both HRP and RR. The phosphotungstic acid-chromic acid stain (PTA-CrA) also reveals glycoproteins in the surface coat; these glycoproteins are susceptible to α-neuraminidase, whereas glycoproteins in the Golgi complexes, lysosomes and in the vesicular complexes of IDC are not. The glycoproteins of the latter are susceptible to 0.1 N NaOH. These findings indicate that IDC produce different kinds of glycoprotein, one of which may be secreted and act as a factor for stimulating peripheral T-lymphocytes. Intimate contact between IDC's and PCV's could be observed. It is therefore conceivable that IDC's play an important role in the homing of T-lymphocytes.
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    Ultrastructural study of the prothoracic glands of Galleria mellonella L. in the penultimate, last larval, and pupal stages (1975)
    Springer
    Cell & tissue research 158 (1975), S. 269-280 
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    ISSN: 1432-0878
    Keywords: Prothoracic glands ; Insects ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Prothorakaldrüse von Galleria mellonella (PGL) ist ein Y-förmiges, gepaartes Organ, das aus 45–50 polyploiden Riesenzellen besteht. Die PGL Zellen sind durch neurosekretorische Axone versorgt. Die Entleerung von neurosekretorischen Granula (1000–1300 Å Durchmesser) konnte oft direkt an der Oberfläche von PGL Zellen beobachtet werden. In Anbetracht der Feinstruktur der Zellen können die zwei letzten Larvenstadien in drei Phasen eingeteilt werden: 1. Restitutionsphase gleich nach der Häutung; 2. Stufenweise Aktivierung während der mittleren Phase der ‚'Inter-Häutung”, wie durch den logarithmischen Zuwuchs an Zellgröße, die Abnahme des nukleozytoplasmatischen Verhältnisses und die Zunahme der Zahl der an der Proteinsynthese teilnehmenden Zellorganellen und deren strukturelle Veränderungen bewiesen wurde; 3. ‚'Entleerungsperiode” vor der Häutung, charakterisiert hauptsächlich durch die extreme Erweiterung von peripheren Invaginationen. Vom präpupalen Stadium an wird die zelluläre Aktivität asynchron. Ein Teil der Zellen weist bereits die Zeichen der Involution auf, während andere Zellen erst nach der Aktivierungsphase, die der Häutung folgt, histolysieren. PGL ist eine larvales Gewebe. Während der Aktivierung ändert sich seine Feinstruktur als Funktion der Juvenilhormon-Konzentration (JH), mangels dessen die Drüse histolysiert. In Anbetracht des Gesagten schien uns die Prothorakaldrüse ein geeignetes Modell für die zytologische Untersuchung des Wirkungsmechanismus von JH zu sein.
    Notes: Summary The prothoracic gland (PGL) of Galleria mellonella is a Y-shaped, paired organ, consisting of 45–50 polyploid giant cells. The PGL cells are supplied by neurosecretory axons; release of neurosecretory granules (1000–1300 Å in diameter) directly on the surface of PGL cells was frequently observed. Based on ultrastructure, the last two larval instars can be divided into three phases: 1) restitutive phase immediately after moulting; 2) gradual activation in mid-intermoult as indicated by the logarithmic cell growth, decrease of nucleo-cytoplasmic ratio, increase in the number of cell organelles participating in protein synthesis, and the structural changes of these organelles; 3) “release” period preceding moulting, characterized mainly by the extreme dilatation of peripheral invaginations. From the prepupal stage onward cellular activity is asynchronous. Part of the cells already show the signs of involution, while others histolyse only after the activation phase subsequent to moulting. PGL in G. mellonella. is one of the larval tissues. In the course of activation its ultrastructure changes as a function of juvenile hormone (JH) concentration, in the absence of which it histolyses. Accordingly, it has seemed to us to be a suitable model for the cytological study of JH activity.
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    Structure of the toad epidermis during the moulting cycle (1975)
    Springer
    Cell & tissue research 159 (1975), S. 459-483 
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    ISSN: 1432-0878
    Keywords: Moulting cycle ; Epidermis ; Bufo bufo ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes in the ultrastructure of the toad epidermis during the moulting cycle are described on the basis of 17 skin preparations fixed in consecutive phases of the cycle. Our previous light microscopical findings that morphological changes are mainly restricted to a short period prior to and after shedding are confirmed. Differentiation of zonulae occludentes in the new replacement layer after shedding is described and discussed in relation to the changes in ion permeability after the moult. Changes in appearance and distribution of filaments and of two different types of granules during the moulting cycle are described and discussed in relation to current views on amphibian keratinization; it is concluded that the initial phase of keratinization in the toad is very rapid and with a high degree of synchrony, whereas the laying-down of interfibrillar, central dense matrix in the new stratum corneum takes up to 24 hours and is less synchronous. The separation of the old stratum corneum from the replacement layer is gradual; it may be accomplished by rupture of “ pillars ” bearing the desmosomal complexes between stratum corneum and the replacement layer, or by breaking within the desmosomes themselves. Observed changes in granular content of the replacement layer are considered of no importance for this process, since the time sequence of discharge into the subcorneal space is not correlated with the initiation of separation. Other possible mechanisms of separation are discussed.
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    Structure and histochemistry of the normal intestine of the fowl (1975)
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    Cell & tissue research 160 (1975), S. 125-138 
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    ISSN: 1432-0878
    Keywords: Avian intestine ; Duodenum ; Ultrastructure ; Crypt cells ; Paneth cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the development and maturation of intestinal chief cells from the duodenal crypts of the fowl has been described in detail. Three areas within the crypt can be recognised: (1) the crypt base where cell division is frequent but cell development is minimal; (2) the mid-crypt region where rapid growth and development of the cells takes place; and (3) the zone of differentiation where final development and functional maturation occurs. The structure of the fowl's intestinal crypt is very similar to that described for the mammal. The results are discussed in relation to previous histochemical studies.
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    Acrosome formation and the centriolar complex in the spermatozoa of Sabella penicillum (Polychaeta) (1975)
    Springer
    Cell & tissue research 161 (1975), S. 47-53 
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    ISSN: 1432-0878
    Keywords: Acrosome ; Centriolar complex ; Ultrastructure ; Sabella penicillum (Polychaeta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The acrosomal vesicle of Sabella penicillum spermatids consists of an electrondense core and a more transparent surrounding zone. During subsequent differentiation the vesicle membrane forms several invaginations in the juxtanuclear area. These invaginations later establish contact with the core. In the mature spermatozoon the spaces between the invaginations appear as electron-dense “tubules”; this is probably due to a shift of material from core to periphery. The ultrastructure of the centriolar complex is described in detail.
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    Isometric training of young rats — Effects upon hind limb muscles (1975)
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    Cell & tissue research 161 (1975), S. 225-237 
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    ISSN: 1432-0878
    Keywords: Muscle adaptation to isometric training (Rat) ; Muscle fiber types ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The soleus, reetus femoris, and gastrocnemius muscles of young rats trained isometrically for 4 weeks were studied by light and electron microscopy.—The percentage of fast-twitch oxidative muscle fibers decreased at the cost of the fast-twitch glycolytic fibers in the rectus femoris muscle. The percentages of the slow-twitch oxidative fibers did not change significantly in any of the muscles studied. The changes in the areas of the muscle fibers were specific for the muscle and the fiber type and indicate geometrical rearrangements of the fibers in the trained muscles. The Z and M lines were broader in the soleus (containing about 85% slow-twitch oxidative fibers) than in the rectus femoris muscle (containing about 90% fast-twitch glycolytic fibers), while the sarcomere length and the pseudo-H zone were similar. The length of the myosin filaments appeared to be slightly shorter in the fast rectus femoris than in the slow soleus muscle.—The hypothesis on the temporal progress of muscle adaptation to training (Müller, 1974) was substantiated. Correlations between biochemical (Exner et al., 1973a) and histochemical parameters measuring the oxidative capacity were preserved during adaptation to training. The comparison of the histochemical results with the physiological data on similar animals (Exner et al., 1973a) suggests a complex relationship between the contraction time and the percentage of fast-twitch muscle fibers.
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    Ultrastructure of the adenohypophysis in the teleost Poecilia latipinna (1975)
    Springer
    Cell & tissue research 161 (1975), S. 239-261 
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    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Teleosts (Poecilia, latipinna) ; Cell types ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the sailfin molly, Poecilia latipinna, seven morphological endocrine celltypes could be distinguished with the electron microscope. Each of these was identified with one of the seven cell-types distinguished with the light microscope, to most of which endocrine functions have previously been allocated. Corticotrophs and prolactin cells form the rostral pars distalis, and the proximal pars distalis consists of an outer layer of gonadotrophs and an inner zone containing growth hormone cells and thyrotrophs. The pars intermedia contains two cell-types, of uncertain function. Stellate cells (interstitial cells) occur throughout the adenohypophysis, but are most numerous and prominent in the rostral pars distalis. The inner proximal pars distalis contains a cell-type not previously distinguished in this species with the light microscope, the Z-cell, which could be aminergic. The ultrastructural features of each cell-type are described in detail, and discussed in comparisons with the homologous cells described in other teleosts. There is good agreement for different teleosts in the ultrastructural details of each cell type.
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    Ultrastructure of the taste bud of the human fungiform papilla (1975)
    Springer
    Cell & tissue research 161 (1975), S. 1-10 
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    ISSN: 1432-0878
    Keywords: Human fungiform papilla ; Taste bud ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The taste bud of the human fungiform papilla was examined by electron microscopy. Typical type I, type II, and type III cells were found along with contact sites with nerve endings. Vesicles in nerve fibers contacting type I and type II cells suggest that these cells may receive efferent impulses, whereas vesicles and granules in type III cells adjacent to (afferent) nerve fibers support the view that type III cells are sensory receptors. All of these features are virtually indistinguishable from those previously reported in fungiform taste buds of other mammals.
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    URL: http://dx.doi.org/10.1007/BF00222109
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    Synaptic morphology of the carotid body of the domestic fowl (1975)
    Springer
    Cell & tissue research 162 (1975), S. 459-473 
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    ISSN: 1432-0878
    Keywords: Carotid body ; Domestic fowl ; Reciprocal synapses ; Afferent axons ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Efferent and reciprocal synapses have been demonstrated in the carotid body of the domestic fowl (Gallus gallus domesticus). Synapses were also found with purely afferent morphology, but were probably components of reciprocal synapses. The general morphology of the endings suggested the presence of two types of axon, afferent axons making reciprocal and perhaps afferent synapses with Type I cells, and efferent axons making efferent synapses with Type I cells. A few axo-dendritic synapses were also found. The dense-cored vesicles associated with the afferent components of reciprocal synapses and with the possible true afferent synapses varied in diameter and core but could belong to one population of presynaptic vesicles. These observations are consistent with a new theory for the carotid body receptor mechanism. This proposes a spontaneously discharging afferent axon inhibited by an inhibitory transmitter substance released by the Type I cell via the “afferent” component of its reciprocal synapse, the “efferent” component inhibiting this release. Besides this chemoreceptor modulation of its afferent axon, the Type I cell may also have a general secretory function.
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    URL: http://dx.doi.org/10.1007/BF00209346
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    The dependence of annulate lamellae formation on the nucleus in parthenogenetic rabbit eggs (1975)
    Springer
    Cell & tissue research 162 (1975), S. 475-481 
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    ISSN: 1432-0878
    Keywords: Annulate lamellae ; Parthenogenone ; Ultrastructure ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previously it has been shown that, in the rabbit, although annulate lamellae (AL) are absent in the follicular oocytes, they appear in the fertilized eggs after the formation of the pronuclei. Furthermore, neither pronuclei nor AL appear when unfertilized eggs are aged in vivo or in vitro. This study was undertaken to determine whether AL formation requires presence of an intact nucleus, or whether the sperm alone contains the stimulatory factors essential to AL synthesis. Rabbit eggs were exposed to 10°C, then incubated for 24 hours. Control eggs were incubated without cold-treatment. Electron microscopic observations indicated that two-thirds of the eggs formed one or two ‘pronuclei,’ or subnuclei. The remainder one-third of the cold-treated eggs and the control eggs failed to form ‘pronuclei.’ AL were present in large amounts only in those activated eggs (parthenogenones) which formed ‘pronuclei.’ AL were absent in the control and the non-activated experimental eggs, both of which failed to form a ‘pronucleus.’ A few small AL were observed in eggs with subnuclei. Condensed fine textured nucleoli appeared precociously during cold-treatment in some eggs and they were present in the ‘pronuclei’ of activated eggs. It was concluded that the sperm is not necessary for AL formation, but the presence of an intact nucleus is mandatory.
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    URL: http://dx.doi.org/10.1007/BF00209347
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    Electron microscope studies on the intermediate lobe of the embryonic mouse (1975)
    Springer
    Cell & tissue research 164 (1975), S. 11-26 
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    ISSN: 1432-0878
    Keywords: Intermediate lobe ; Mouse ; Growth and development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the intermediate lobe of the hypophysis was studied in the embryonic C3H mouse; at least four glands from embryos of every gestational day from 15 to 19 were examined. In the 16 day-old embryo prospective secretory cells proliferate at the centre of the intermediate lobe anlage. At the same stage cylindrical cells bordering the hypophyseal cleft begin to reorganize into marginal cells. By the end of fetal life marginal cells are well differentiated. In the 17 day-old embryo a few granular inclusions appear in some centrally located cells. Secretory cells increase in number during the following two embryonic days. Some of these cells contain polymorphic populations of granular and vesicular inclusions by gestational day 19. The possibility of a dual formation of secretory inclusions is discussed. The result implies that the onset of granule-formation by these cells is not contemporaneous with the start of production of melanophore-expanding substances, the presence of which has been detected by earlier biological assays.
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    URL: http://dx.doi.org/10.1007/BF00221692
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    The development and fine structure of ultimobranchial glands in larval anurans (1975)
    Springer
    Cell & tissue research 164 (1975), S. 215-232 
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    ISSN: 1432-0878
    Keywords: Ultimobranchial glands ; Anuran larvae ; Metamorphosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A comparative optical microscopic and ultrastructural study on the ultimobranchial (UB) glands of three common species of Israeli anurans: Bufo viridis, Hyla arborea, and Rana ridibunda during metamorphosis is presented. The UB glands typically consist of a single follicle with a central lumen, though occasionally secondary follicles are present in Hyla and Rana. A single UB cell type is found which appears either in a very electrondense “dark” form or as a less dense “light” form, though the ratio of dark: light cells from gland to gland at any one stage of metamorphic development is quite variable. By the end of metamorphosis in Bufo and Hyla all the UB cells are usually of the light variety, whereas in Rana the dark cells persist. The organelles of these secretory cells including secretory granules, granular endoplasmic reticulum, free ribosomes, tonofilaments, microtubules, Golgi bodies, and lipid droplets, their distribution, abundance, and possible functions in relation to metamorphosis are described. Apocrine secretion into the central lumen of the gland is also described and discussed.
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    URL: http://dx.doi.org/10.1007/BF00218975
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    The ultrastructure of the swimbladder of the toadfish, Opsanus tau L. (1975)
    Springer
    Cell & tissue research 164 (1975), S. 85-104 
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    ISSN: 1432-0878
    Keywords: Swimbladder ; Opsanus tau ; Physoclist ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anterior chamber of the swimbladder of the toadfish Opsanus tau L. is lined by a single layer of columnar gas gland cells, cuboidal cells that resemble gas gland cells but are located outside of the gas gland region, and squamous cells. Multilamellar bodies are numerous in the gas gland cells and the cuboidal cells and are present in smaller numbers in the squamous cells. Capillaries lie in the lamina propria directly below the epithelial lining. A thick continuous muscularis mucosae and a submucosa consisting of tightly packed cells, cell processes, and connective tissue may contribute to the impermeability to gases of the wall of the anterior chamber. The posterior chamber of the swimbladder is lined by a single type of squamous epithelial cell. Multilamellar bodies were occasionally observed in these cells also. Other types of cells frequently form a partial second layer between the epithelial lining and the basement lamina. A thin muscularis mucosae lies directly below the basement lamina and the capillaries of the posterior chamber are located in the submucosa. The tunica externa is a layer of dense connective tissue that surrounds both the anterior and posterior chambers. Collagen fibrils in the form of tactoids are present in this layer.
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    URL: http://dx.doi.org/10.1007/BF00221697
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    Ultrastructural changes in granulosa lutein cells and progesterone levels during preimplantation, implantation, and early placentation in the western spotted skunk (1975)
    Springer
    Cell & tissue research 164 (1975), S. 179-192 
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    ISSN: 1432-0878
    Keywords: Granulosa lutein cells ; Western spotted skunk ; Ultrastructure ; Progesterone levels ; Implantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of corpora lutea obtained during the preimplantation, implantation and early postimplantation periods has been studied in 20 western spotted skunks. Fine structure of granulosa lutein cells was correlated with progesterone levels. The corpus luteum of the prolonged (7 month) preimplantation period contained undifferentiated small granulosa cells and differentiated large granulosa lutein cells. The former ranged in size between 12 and 20 μ and the latter between 20 and 45 μ. The ratio of small and large cells was about equal in an animal 2 days prior to nidation whereas only few small cells and numerous large cells were observed in an animal estimated to be 8 to 12 hours from nidation. Occasionally small cells were observed amidst large ones during the 24 hour nidation period, i.e. adhesion of trophoblast with the luminal uterine epithelium, but small cells were absent in animals after this period. Small cells had some smooth and rough endoplasmic reticulum, rod-shaped mitochondria with platelike cristae, small Golgi complex, and relatively smooth plasma membranes. Large lutein cells had abundant smooth endoplasmic reticulum, membranous whorls of smooth endoplasmic reticulum, usually round mitochondria with tubular and lamellar cristae, a well developed Golgi complex, variable amounts of lipid droplets, and highly plicated and ruffled plasma membranes. Peripheral plasma progesterone levels during the prolonged preimplantation period ranged between 1.1 and 7.9 ng/ml, but during implantation it was between 8 and 16.6 ng/ml. It is suggested that plasma progesterone levels fluctuate during the time of implantation and should not be regarded as a basis to predict actual nidation in the western spotted skunk.
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    URL: http://dx.doi.org/10.1007/BF00218972
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    Concentration of dopaminergic fibres in the marginal zone of the bird retina (1976)
    Springer
    Cell & tissue research 173 (1976), S. 335-341 
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    ISSN: 1432-0878
    Keywords: Bird marginal retina ; Ultrastructure ; Histofluorescence ; Dopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve fibres containing dense core vesicles of 100–160 nm diameter are concentrated in a narrow zone (near the ora serrata) of the marginal retina in the pigeon and the chicken. Synaptic junctions exist between terminals containing dense core vesicles and the most marginal ganglion cells; however, numerous fibres seem to end freely near the vitreous body or even penetrate the pars plana of the ciliary body. Histofluorescence demonstrates the aminergic nature of these fibres. Determination of catecholamines with the dansylation technique reveals six times more dopamine in the marginal than in the central retina, whereas the noradrenalin level is unchanged. The dopaminergic fibres originate in neurons of the innermost zone of the inner nuclear layer. The marginal localisation of these fibres apparently excluding any visual function seems rather to indicate a possible photoreceptor system involved in neuro-endocrine regulation.
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    URL: http://dx.doi.org/10.1007/BF00220321
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    The fine structure of fins and finrays of Tilapia mossambica (Peters) (1976)
    Springer
    Cell & tissue research 173 (1976), S. 349-356 
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    ISSN: 1432-0878
    Keywords: Finrays ; Tilapia ; Ultrastructure ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron-microscopic studies were carried out on the fins of the fish Tilapia mossambica (Peters). A detailed description is presented of the different skeletal components comprising the finrays. The mode of development of the hemisegments appears in several ways similar to that of fish scales. Each hemisegment is contained by an envelope of scleroblasts which secrete collagen fibres in a unipolar fashion. Calcification takes place as a result of deposition of hydroxyapatite-like crystals between the collagen fibres. However, the orientation of these fibres is not as regular as that of the fibres occurring in scales.
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    URL: http://dx.doi.org/10.1007/BF00220323
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    Stretch receptors in urodele limb muscles (1976)
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    Cell & tissue research 165 (1976), S. 249-266 
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    ISSN: 1432-0878
    Keywords: Stretch receptor ; Urodele amphibia ; Ultrastructure ; Physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Non-encapsulated, fine beaded nerve endings were found histologically on some muscle fibres in a number of limb muscles in newts and axolotls. They were present in newt muscles that had been chronically de-efferented, and in which no efferent activity survived, and were therefore likely to be sensory. They were located only on muscle fibres on or near the outside surface of the muscle. These small-diameter muscle fibres were characterised histochemically by low lipid, SDH and phosphorylase content; ultrastructurally by low glycogen content, and relatively large myofilaments poorly delimited by a sparse SR. There were many of this type (Type 1) that did not support sensory endings. A few endings occurred on another larger-diameter type of fibre (Type 2) whose properties were opposite to those listed above for Type 1. There was virtually no specialization of muscle fibre structure beneath the sensory endings. Physiological experiments involving ramp-and-hold and sinusoidal stretch applied to the muscle whilst recording single-unit afferent responses in m.ext. dig. III of axolotls showed unit responses very similar to those known from muscle spindles, particularly those of the frog.
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    URL: http://dx.doi.org/10.1007/BF00226663
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    Ultrastructure of the compound eye of the diploid female beetle, Xyleborus ferrugineus (1975)
    Springer
    Cell & tissue research 165 (1975), S. 23-36 
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    ISSN: 1432-0878
    Keywords: Sensory receptor ; Compound eye ; Insect ; Ultrastructure ; Scanning and transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye of female (diploid) Xyleborus ferrugineus beetles was examined with scanning and transmission electron microscopy. The eye is emarginate, and externally consists of roughly 70–100 facets. Each ommatidium is composed of a thickly biconvex lenslet with about 50 electron dense and rare layers. The lens facet overlies a crystalline cone of the acone type which is roughly hourglass-shaped. Pigment cells envelop the entire ommatidium, and pigment granules also are abundant throughout the cytoplasm of the 8 retinular cells. The rhabdomeres of 2 centrally situated photoreceptor cells effectively fuse into a rhabdom that extends from the base of the crystalline cone deeply into the ommatidium. Six distal peripheral retinular cells encircle the 2 central cells, and their rhabdomeres join laterally to form a rhabdomeric ring around the central rhabdom. The rhabdom and rhabdomeric ring are effectively separated by the cytoplasm of the two central retinular cells which contains the usual organelles and an abundance of shielding pigment granules. Eight axons per ommatidium gather in a tracheae-less fascicle before exiting the eye through the fenestrate basement membrane. No tracheation was observed among the retinular cells. Each Semper cell of each observed crystalline cone contained an abundance of virus-like particles near the cell nucleus. The insect is laboratory reared, and the visual system seems very amenable to photoreceptor investigations.
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    URL: http://dx.doi.org/10.1007/BF00222797
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    Ultrastructure of the milk fat globule membrane with and without triglyceride (1975)
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    Cell & tissue research 165 (1975), S. 113-127 
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    ISSN: 1432-0878
    Keywords: Milk fat globule ; Membrane ; Triglyceride content ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The primary milk fat globule membrane (MFGM) around freshly secreted milk fat globules consists of a unit membrane separated from the triglyceride core by a dense material. This dense material may widen to include cytoplasmic organelles or may form small blebs. Preincubation and fixation of the globules at temperatures between 4° C and 60° C has no effect on the width or appearance of the dense material. Isolated MFGM profiles show structures identical to those found on intact globules. The dense material on the isolated MFGM profiles is unaffected by extractions which remove essentially all the triglyceride present in the pellets of MFGM. The structure of the primary MFGM is therefore independent of any triglyceride content and the earlier suggestions that the dark material represented a triglyceride layer of high melting point adsorped during cooling of the globules after milking are not supported by the work described in this paper.
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    URL: http://dx.doi.org/10.1007/BF00222804
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    Neurosecretion in the sinus gland of the fiddler crab, Uca pugnax (1975)
    Springer
    Cell & tissue research 165 (1975), S. 129-133 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Eyestalk ; Ultrastructure ; Uca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the sinus gland of the fiddler crab, Uca pugnax, was investigated and found to be similar to that in other crustaceans. Five types of neurosecretory axon terminals were tentatively identified on the basis of the size, shape, and electron density of granules within the axons. Release of neuro-secretory material appears to be by exocytosis.
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    URL: http://dx.doi.org/10.1007/BF00222805
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    The saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson (1976)
    Springer
    Cell & tissue research 167 (1976), S. 467-491 
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    ISSN: 1432-0878
    Keywords: Saccus dorsalis, Salmo gairdneri Richardson ; Histology ; Ultrastructure ; Cytochemistry ; Enzyme-cytochemistry ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The saccus dorsalis of the brain of the rainbow trout, Salmo gairdneri Richardson, has been investigated by means of histological, cytochemical, enzyme-cytochemical, electron microscopical and autoradiographical techniques. The saccus dorsalis is a rostro-dorsal evagination of the diencephalic roof, and consists of a partly folded epithelial wall separating the cerebrospinal fluid from the meningeal matrix fluid. The well-developed vascular system around the epithelial wall, consisting of capillaries with different diameters, seems to be part of the pineal vascular system. No structures were found that may be involved in a possible mechanical or nervous blood flow control. The single-layered epithelium consists of highly specialized cells of one specific type. These cells are mainly characterized by infolded basal membranes, long microvilli of a peculiar shape, non-folded lateral membranes bordering intercellular spaces, apical concentrations of elongate and cupshaped macromitochondria, a basally located rough endoplasmic reticulum, an apically situated smooth endoplasmic reticulum and apical concentrations of micropinocytotic vesicles. Morphological evidence is presented of a multiple function of these cells: (1) fluid secretion, (2) extrusion of low molecular weight organic substances into the ventricular system, (3) uptake of high molecular weight substances, and (4) uptake of low molecular weight organic substances (aminergic neurotransmitters [GABA]) from the cerebrospinal fluid. The significance of light and dark cells is discussed. Indications of a possible innervation of the saccus dorsalis epithelial cells were not observed. The functional significance of the saccus dorsalis (possible analogue of the choroid plexus?) is discussed.
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    Retinal alterations induced by continuous light in immature rats (1976)
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    Cell & tissue research 166 (1976), S. 201-211 
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    ISSN: 1432-0878
    Keywords: Electroretinography ; Retinal degeneration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immature albino rats were exposed to continuous illumination for 5–93 days and the light induced ultrastructural and electroretinographic changes were studied. Another group was exposed to continuous light for 7–9 days and then kept in complete darkness, or in cyclic light-dark up to 90 days. By comparison with the results obtained in adult animals, lesions appeared faster in the immature group. Tubular transformation of rods, phagocytosis of altered outer and inner segments with resulting changes in retinal organization, synaptic degeneration in the outer plexiform layer, and cell lysis of some photoreceptor cell perikarya are described. ERG recovery, following the period of darkness or cyclic light-dark, was only partial, the amplitude of the “b” wave reached only 50–60% of the control preillumination values. However, the fine structure of the recovered outer segments was similar to that found in normal retinae.
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    A cell type in sponges involved in the metabolism of glycogen (1977)
    Springer
    Cell & tissue research 175 (1977), S. 523-539 
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    ISSN: 1432-0878
    Keywords: Sponge ; Gray cell ; Glycogen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gray cells of four orders of demosponges contain basophilic inclusions and glycogen. They are capable of synthesis and accumulation of glycogen and responsible for its transfer to sites of more intense metabolism (growth, bud, blastema). They do not occur in larvae; but all the phases of their differentiation from the flagellar cells of the larva have been demonstrated.
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    Correlation between suckling-induced changes in the ultrastructure of mammotrophs and prolactin release (1976)
    Springer
    Cell & tissue research 166 (1976), S. 399-406 
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    ISSN: 1432-0878
    Keywords: Mammotrophs ; Prolactin ; Lactation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Effects of suckling on the structure of mammotrophs and the release of prolactin, were studied in rats on the 10th day of lactation with the use of electron microscopy and radioimmunoassay techniques. Nursing animals were separated from their young for 8 hr and subsequently united and permitted to nurse for 1, 5, 15, 30 min; or 1, 2 and 4hr. Blood samples were obtained prior to and throughout the suckling interval and pituitary glands were processed for electron microscopy. Control animals consisted of normal lactating females and animals separated from their young for 8 hr. Normally lactating controls had high prolactin serum levels (501±95 ng/ml) and synthetically active appearing mammotrophs. An 8 hr separation from the pups induced a dramatic lowering of serum prolactin (32±5 ng/ml), an increase in secretory granule storage, and a great dilation of rough endoplasmic reticulum (RER) cisternae. Five min of renewed suckling resulted in a rise of plasma prolactin levels (605±183 ng/ml) which remained high thereafter. The major ultrastructural changes observed during the first 30 min of suckling were as follows: 1) at 1 min, the RER became collapsed suggesting a discharge of its contents (soluble hormone?); 2) at 5 min, and much more obviously at 15 and 30 min, a massive discharge of secretory granules was observed; and 3) at 15 and 30 min, the collapsed RER underwent transformation from lamellar into a vesicular form. Prolonged suckling (for 1, 2 and 4 hr) induced new hormone synthesis as suggested by the presence of hypertrophied Golgi elements and numerous immature granules. This was accompanied by a new transformation of the RER from the vesicular into a lamellar form now consisting of very slender cisternae lined with numerous ribosomes, presumably involved in the renewal of the synthetic process. The morphologic findings described correlate well with the time table of prolactin release. In addition, the dramatic early changes in the structure of the RER suggest a possible involvement of this organelle in the storage and release of a proposed rapidly releasable pool of prolactin.
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    URL: http://dx.doi.org/10.1007/BF00220134
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    Neurosecretory cell types in the eyestalk of the freshwater prawn Palaemon paucidens (1976)
    Springer
    Cell & tissue research 166 (1976), S. 511-520 
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    ISSN: 1432-0878
    Keywords: Neurosecretory cells ; Eyestalk ; Palaemon ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the medulla terminalis ganglionic X-organ (MTGX) of the eyestalk of the freshwater prawn, Palaemon paucidens, six peptidergic neuro-secretory cell types (A-, B-, C-, D-, E-, and F-cells) are distinguishable on the basis of the different morphology of their elementary granules and rough endoplasmic reticulum (rER). All of these cell types seem to correspond to Type-IIIa cells or dispersing Type-IV cells, that have previously been differentiated at the light microscopic level (Hisano, 1974), as judged from the dimensions of their cell bodies and nuclei. Two other peptidergic neurosecretory cell types that are apparently comparable to the Type-II and Type-IIIb cells (Hisano, 1974), respectively, are recognized in parts of the optic ganglia other than MTGX, and these are now designated as Gand H-cells, respectively. All the remaining cell types, designated as Type-I, cluster-forming Type-IV, Type-V and Type-VI cells in our previous light microscopic study, have small cored-vesicles in their cytoplasm. It remains undecided whether these, possibly aminergic, neurons are neurosecretory or not.
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    URL: http://dx.doi.org/10.1007/BF00225915
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    The fine structural localization of testicular phosphatases in man: The control testis (1976)
    Springer
    Cell & tissue research 166 (1976), S. 497-510 
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    ISSN: 1432-0878
    Keywords: Spermatogenesis ; Phosphatase cytochemistry ; Ultrastructure ; Testis ; Male reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic cytochemistry was used to determine the localization of five phosphatase enzymes—glucose-6-phosphatase, inosine diphosphatase, thiamine pyrophosphatase, acid phosphatase, and adenosine triphosphatase—in control human testes. Glucose-6-phosphatase occurred in the endoplasmic reticulum and nuclear envelope of Sertoli cells, Leydig cells and primitive spermatogonia, but was not observed in more advanced spermatogenic cells. The presence of glucose-6-phosphatase activity paralleled the presence of glycogen in spermatogenic cells, i.e., both occurred in type AL and AD spermatogonia but not in type AP or B spermatogonia or in more advanced spermatogenic cells. Inosine diphosphatase activity was found in the endoplasmic reticulum, nuclear envelope, and Golgi complex of Sertoli cells and all spermatogenic cells except late spermatids. Additionally, inosine diphosphatase activity was localized at the junctions between Sertoli cells and late spermatids, but was not associated with any other plasma membrane. Thiamine pyrophosphatase reaction product was found in the Golgi bodies of Sertoli cells and in spermatogenic cells through immature spermatids. Neither inosine diphosphatase nor thiamine pyrophosphatase was observed in the Golgi bodies of spermatids during acrosomal formation. Acid phosphatase activity was found in lysosomes of spermatogonia, spermatocytes, and spermatids, in lysosomes of Leydig cells, and in lysosomes, lipofuscin bodies, and Golgi cisternae of Sertoli cells. It is thought that Sertoli lysosomes play a role in the phagocytosis of degenerating germ cells; however, the role of spermatogenic or Leydig lysosomes is unknown. Adenosine triphosphatase activity occurred at the interfaces between two spermatogonia, and between Sertoli cells and spermatogonia, but was not observed in the spaces between two Sertoli cells, two spermatocytes, two spermatids, or between Sertoli cells and spermatocytes, or between Sertoli cells and spermatids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225914
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  • 94
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    Excitatory synapses of blue crab gastric mill muscles (1977)
    Springer
    Cell & tissue research 177 (1977), S. 145-158 
    Details
    ISSN: 1432-0878
    Keywords: Neuromuscular synapse ; Crustacean ; Ultrastructure ; Physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Physiological and ultrastructural studies were made of neuromuscular synapses in stomach muscles, especially two gastric mill muscles of the blue crab innervated by neurons of the stomatogastric ganglion. These muscles depolarized and contracted with application of glutamate, but not acetylcholine, whereas the dorsal dilator muscles of the pyloric region depolarized and contracted in acetylcholine, but not in glutamate. Large excitatory postsynaptic potentials (EPSP's) of 5–20 mV were recorded in the gastric mill muscles. At low frequencies of activation, individual synapses released on average about 2 quanta of transmitter for each nerve impulse. Facilitation of EPSP's after a single nerve impulse could be detected for at least 10 s. Synapses were found on enlarged terminals of the motor axon; their contact areas ranged from 0.2 μm2 up to 3 μm2. Both electron-lucent, round synaptic vesicles and dense-cored vesicles occurred near these synapses. A possible correlation between contact area of a synapse and output of transmitter, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221078
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  • 95
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    Ultrastructure of the compound eye of the haploid male beetle, Xyleborus ferrugineus (1976)
    Springer
    Cell & tissue research 168 (1976), S. 315-324 
    Details
    ISSN: 1432-0878
    Keywords: Sensory receptor ; Compound eye (Xyleborus ferrugineus) ; Male insect ; Ultrastructure ; Scanning and transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye of male (haploid) Xyleborus ferrugineus beetles was examined with scanning and transmission electron microscopy. The eye externally consists of ca. 19 to 33 facets. Each ommatidium is composed of a thickly biconvex lenslet with about 50 electron dense and rare layers, but at the junction area between two lenslets there are only about 35 to 37 layers that can be distinguished. A very short (3.4–4.0 μm) acone type crystalline cone is located directly beneath the lenslet. Each ommatidium is surrounded by pigment cells, and pigment granules also appear throughout the cytoplasm of the retinular cells. Some pigment granules are even present below the basement membrane. There are 8 retinular cells. The rhabdomeres of 2 centrally situated photoreceptor cells fuse into a rhabdom which is enveloped by the rhabdomeres of 6 peripheral retinular cells. The rhabdomeres of the 6 peripheral retinular cells join laterally to form a rhabdomeric ring around the central rhabdom. No tracheation was observed among the retinular cells. Virus-like particles are evident near the nucleus in each Semper cell of the crystalline cone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215309
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  • 96
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    Effect of calcium depletion and subsequent repletion on parathyroids, parafollicular (C) cells and bone in the growing pig (1976)
    Springer
    Cell & tissue research 168 (1976), S. 373-384 
    Details
    ISSN: 1432-0878
    Keywords: Calcium ; Bone ; Parathyroid ; Parafollicular cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the chief cells of the parathyroid gland and thyroid parafollicular (C) cells and the morphology of bone in calcium depletion and subsequent repletion were examined in young growing pigs. A low calcium diet resulted in osteopenia, increased removal of the cartilaginous core, osteoclasia and osteocytic osteolysis. Subsequent repletion quickly returned bone to normal. In pigs fed the low calcium diet, there was a marked depletion of secretory granules but a striking increase in the number of microtubules in chief cells. Increasing the calcium content of the diet to normal quickly returned the ultrastructural appearance of chief cells to apparent normal. In the initial response to calcium repletion, chief cells exhibited large number of lysosomes and occasionally prominent paracrystalloid bodies. Electron microscopic examination of parafollicular (C) cells of the thyroid gland failed to reveal differences in ultrastructure between test and control pigs. These findings support the view that bone resorption following calcium deficiency may be the result of a secondary hyperparathyroidism rather than of calcium deficiency per se.
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    URL: http://dx.doi.org/10.1007/BF00215314
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  • 97
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    Ultrastructural studies on the vitellogenesis of Tetrodontophora bielanensis (Waga) (Collembola) (1976)
    Springer
    Cell & tissue research 168 (1976), S. 399-410 
    Details
    ISSN: 1432-0878
    Keywords: Vitellogenesis ; Dictyosomes ; Micropinocytosis ; Ultrastructure ; Collembola
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vitellogenesis in Tetrodontophora bielanensis (Waga) is of the “mixed” type. Part of the yolk material is produced inside the oocyte (auto-synthesis), while part is absorbed by micropinocytosis. During autosynthesis polyribosomes, rough endoplasmic reticulum and dictyosomes take part. Regardless of their origin, mature yolk spheres are constructed identically and are composed of three elements: cortex layer, matrix and crystals. Histochemical tests show that polysaccharides are present in the yolk spheres. Lipid droplets have been observed in the ooplasm; they develop without visible contact with any of the organelles. Among the reserve materials the following have been found: rough endoplasmic reticulum, dictyosomes, polyribosomes, mitochondria and a few microtubules.
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    URL: http://dx.doi.org/10.1007/BF00215316
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  • 98
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    Fine structure of the interplatelet area in the gills of the macrophthalmia stage of the river lamprey, Lampetra fluviatilis (L.) (1976)
    Springer
    Cell & tissue research 168 (1976), S. 433-443 
    Details
    ISSN: 1432-0878
    Keywords: Chloride cell ; Gill filaments ; Ultrastructure ; Ion-transport ; Macrophthalmia stage ; Lampetra fluviatilis (L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The interplatelet epithelium of the gills of freshwater and seawater adapted macrophthalmia stages of the river lamprey, Lampetra fluviatilis, was studied by electron microscopy. Three main cell types: basal, ion-excretory and superficial cells were identified and described. Ion-excretory cells were exposed to the environment in sea water but covered by a layer of superficial cells in fresh water. Electron-dense secretory granules in the apex of the cell were more abundant in fresh water. In fresh water, a few of the superficial cells contained numerous mitochondria and were identified as ion-uptake cells. In view of the scarcity of ion-uptake cells, the possibility that the ion-excretory cells are also responsible for ion-uptake in fresh water is discussed. Phagocytic removal of degenerating ion-excretory cells may be an important mechanism for the conservation of materials in a starving animal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215994
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  • 99
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    Fine structural observations on the protonephridium of the terrestrial triclad Geoplana pasipha (1976)
    Springer
    Cell & tissue research 168 (1976), S. 455-463 
    Details
    ISSN: 1432-0878
    Keywords: Protonephridium ; Flatworm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The protonephridial system of the terrestrial triclad Geoplana pasipha was studied by electron microscopy. In general construction it conforms to that of the freshwater planarian Dugesia tigrina (McKanna, 1968, 1968 a). Ultrastructural details permit the identification of proximal, collecting, osmoregulatory and nephridiopore regions. Intralumenal material is frequently observed within the tubules, whose cells are always joined by septate junctions. Cilia are numerous and possibly contribute to the flow of water and solutes along the system. Proximal tubules have a peculiar, particulate membrane coat, while a continuous coat, densely stainable with ruthenium red lines the more distal, unciliated tubules.
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    URL: http://dx.doi.org/10.1007/BF00215996
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  • 100
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    Ultrastructure and permeability of lymph node microvasculature in the mouse (1976)
    Springer
    Cell & tissue research 168 (1976), S. 507-525 
    Details
    ISSN: 1432-0878
    Keywords: Lymph node microvasculature ; Ultrastructure ; Permeability ; Horseradish peroxidase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The microvasculature of lymph nodes and Peyer's patches consists of arterioles, capillaries and venules. The postcapillary segment comprises high-endothelial venules (HE venules) as well as ordinary venules. In order to study the ultrastructure of the microvasculature, particularly with respect to the nature of intercellular junctions, lanthanum and ruthenium red were used as tracers. Furthermore, to evaluate the permeability properties of the different segments of the microvasculature, intravenously injected horseradish peroxidase (HRP; MW: 40,000) was used. All segments of the microvasculature are permeable to HRP. However, the mechanism of transport across the vascular wall varies in the different segments, apparently correlated with a gradual decrease in number of transport vesicles and a gradual attenuation in the sealing of the endothelial cells. Tight junctions are present in arterioles, and it is assumed that HRP reach the basal lamina exclusively by vesicular transport. Incomplete or focal tight junctions are present in the capillaries, and both intercellular and vesicular pathways are observed. In the venules the intercellular pathway seems to be the dominant one, while vesicular transfer is negligible. However, some micropinocytic vesicles in the HE venule endothelial cells probably represent the initial stage of an intracellular digestion.
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    URL: http://dx.doi.org/10.1007/BF00216000
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