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  • Ultrastructure  (74)
  • Springer  (74)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • 1995-1999  (13)
  • 1985-1989  (61)
  • 1980-1984
  • 1997  (13)
  • 1985  (61)
Collection
Keywords
Publisher
  • Springer  (74)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (2)
Years
  • 1995-1999  (13)
  • 1985-1989  (61)
  • 1980-1984
Year
  • 1
    Electronic Resource
    Electronic Resource
    An ultrastructural study of the mature spermatozoid of the fern Asplenium trichomanes L. subsp. trichomanes (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 142-148 
    Details
    ISSN: 1432-2145
    Keywords: Key words Asplenium trichomanes L. subsp. trichomanes ; Ferns ; Spermatozoids ; Flagella ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Asplenium trichomanes L. subsp. trichomanes spermatozoids are spirals of about five turns. Keels link the elements of the microtubular ribbon with the plates of the lamellar layer (LL) which are uninterrupted, parallel and curved with an inner angle of about 150°. Electron-opaque filaments connect the microtubules of the multilayered structure (MLS) and the osmiophilic crest, the LL and the MLS-associated mitochondrion and the latter and the plasmalemma. The nucleus occupies the 2.5–3 posterior turns and has an inner honeycomb-shaped chromatin mass and an outer highly condensed chromatin mass with randomly scattered electron-transparent areas. The basal bodies of the ca. 50 flagella are bounded by a reticulum of granular material which forms a plug inside their proximal region; the proximal region of the flagellum has a 9 + 0 pattern. The axoneme has a 9 + 2 pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050081
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical isolation and ultrastructural characterization of viable egg cells in Plumbago zeylanica (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 368-373 
    Details
    ISSN: 1432-2145
    Keywords: Key words Egg-cell isolation (angiosperm) ; Micromanipulation ; Plumbagozeylanica ; Viable egg ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A protocol for isolating viable eggs in Plumbago zeylanica by mechanical dissection is reported. The optimum solution for isolation was 0.8 M mannitol + 10 mM MOPS + 10 mM CaCl2, (pH 4.5–5.0) with an osmolality of 860–940 mmol/kg. Eggs retain their viability for at least 24 h. Isolated eggs were true protoplasts without cell walls and could tolerate osmolality of 437 mmol/kg to 965 mmol/kg. Observation of the isolated eggs using transmission electron microscopy indicated that they were well preserved and reflected the ultrastructure of physiologically active cells, displaying features similar to those of in vivo egg cells. Notable differences include the absence of a filiform apparatus and the accumulation of dense particles in the plastids, which was most conspicuous in egg cells that were damaged during isolation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050111
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  • 3
    Electronic Resource
    Electronic Resource
    A new cell wall structure in a symbiotic and a free-living strain of the blue-green alga genus Chroococcidiopsis (Pleurocapsales) (1985)
    Springer
    Archives of microbiology 143 (1985), S. 117-121 
    Details
    ISSN: 1432-072X
    Keywords: Cyanophyta ; Chroococcidiposis ; Lichenphycobiont ; Cell wall ; “Outer membrane” ; Ultrastructure ; Freeze fracturing/etching ; Patchwork-like leaflet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freeze etching studies in a symbiotic and a freeliving strain of Chroococcidiopsis revealed a specific layer in the outer cell wall not described so far from Cyanophyta. The layer showed a complex organisation: The main unit are ribbons, 2–3 nm thick, striated at right angle to the longitudinal axis. They are interwoven to a patchwork-like leaflet. The ribbons are virtually composed of globular particles associated in parallel rows. The cytoplasmic membrane and the cell walls of the symbiotic and the free-living strain were compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411033
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  • 4
    Electronic Resource
    Electronic Resource
    Evidence for tight junctions between odontoblasts in the rat incisor (1985)
    Springer
    Cell & tissue research 239 (1985), S. 137-140 
    Details
    ISSN: 1432-0878
    Keywords: Lanthanum ; Odontoblasts ; Tight junctions ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Odontoblasts are known to be involved in the process of dentinogenesis but it is not clear whether substances may also be deposited in predentine and dentine by passing between these cells. Although tight junctions have been described, it is not clear if they are macular or “leaky” as opposed to continuous or “tight”. In this study use has been made of the permeability of fenestrated capillaries amongst the odontoblasts to deposit the penetrative tracer lanthanum in the interodontoblastic space. This was done by perfusion of anaesthetized rats with physiological solutions containing lanthanum nitrate at 37° C. Immersion fixation of transverse segments of mandibular incisors and examination with an electron microscope showed that lanthanum could permeate 40–50 μm between the odontoblasts to reach the peripheral pulp. Towards the predentine, often less than 10 μm from the capillaries, its progress was abruptly and completely halted by the junctions at the apical ends of the odontoblast cell bodies. Lanthanum was not found in the predentine. The mature secretory odontoblasts in the rat incisor have therefore been shown to be joined by continuous tight junctions. In the process of dentinogenesis this means that all substances deposited in predentine and dentine must arrive by passing through the odontoblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214913
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of corpora allata of known activity during the vitellogenic cycle in the cockroach Diploptera punctata (1985)
    Springer
    Cell & tissue research 239 (1985), S. 317-327 
    Details
    ISSN: 1432-0878
    Keywords: Corpora allata ; Ultrastructure ; Juvenile hormone ; Rates of synthesis ; Reproductive cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructure was correlated with rates of juvenile hormone synthesis in corpora allata from females of the viviparous cockroach Diploptera punctata at seven daily intervals during the first vitellogenic cycle. Synthetic activity of the glands was determined by in vitro radiochemical assay before the glands were fixed for electron microscopic analysis. The cycle in rates of juvenile hormone synthesis progressed from about 20 pmol h-1 per gland pair (oocytes 0.60 mm long) to a maximum mean rate of 140 pmol h-1 per pair (oocytes 1.40–1.47 mm long) and declined to about 20 pmol h-1 per pair at ovulation (oocytes about 1.65 mm long). Conspicuous ultrastructural changes occurred with changing synthetic rates. In glands with increasing rates of synthesis, mitochondria showed less electron-dense matrix, greater diameter and more irregular shape. Smooth endoplasmic reticulum changed from easily seen to obscure tubules, networks, and vesicles. Rough endoplasmic reticulum appeared in longer, more curved segments. Newly formed autophagic vacuoles appeared in all glands of highest activity rates. In glands with decreasing rates of synthesis, the mitochondrial matrix became denser, width smaller, and shapes less irregular. Smooth endoplasmic reticulum again appeared tubular and distinct. Golgi complexes were more conspicuous. Rough endoplasmic reticulum in whorls and large numbers of autophagic vacuoles continued to be present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218010
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  • 6
    Electronic Resource
    Electronic Resource
    Electron-microscopic studies on the physiological cell loss in the gastric mucosa of the golden hamster (1985)
    Springer
    Cell & tissue research 239 (1985), S. 343-347 
    Details
    ISSN: 1432-0878
    Keywords: Gastric mucosa ; Surface mucous cell ; Physiological cell loss ; Cell renewal ; Ultrastructure ; Golden hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fine-structural aspects of physiological cell loss in the gastric mucosa of the golden hamster were observed. As the surface mucous cell ascends along the gastric pit, the cell becomes taller and funnel-like in shape. The interfoveolar cell located at the superficial portion of the gastric pit has many lysosomes and a few lipid droplets in the cytoplasm. The nucleus moves toward the upper region of the cytoplasm, while the Golgi apparatus moves downward toward the infranuclear region. After the rupture of the apical plasma membrane takes place, the lateral and basal plasma membranes of this cell remain in spite of loss of the cell contents. Between the basal plasma membrane of the interfoveolar cell and the capillary endothelium is a thick connective tissue layer characterized by densely packed collagen fibrils. The remaining basal and lateral plasma membranes of the ruptured cell and the thick underlying collagenous layer might play a role in protecting the tissue from potential damage induced by the physiological cell loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218013
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in the spleen of the natterjack, Bufo calamita, after antigenic stimulation (1985)
    Springer
    Cell & tissue research 239 (1985), S. 435-441 
    Details
    ISSN: 1432-0878
    Keywords: Spleen ; Dendritic cells ; Ultrastructure ; Immunization ; Bufo calamita
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study comparative aspects of the ultrastructure of the spleen were analyzed in non-immunized and T-dependent antigen-challenged natterjacks, Bufo calamita. Special attention is focused on the role of the non-lymphoid components in the splenic immunoreactivity. Ten days after primary immunization with sheep erythrocytes, splenic lymphoid follicles increase considerably in number and size. By that time, lymphoblasts, medium and large lymphocytes abound in the periphery of the white pulp near the marginal zone. Meanwhile, in the red pulp numerous monocytes migrating across the sinusoidal walls apparently transform into giant, dendritic-like cells. Twenty days after immunization the splenic lymphoid follicles decrease in number, although certain reactivity persists and numerous plasma cells occur in the cell cords and sinusoids of the red pulp. These results are discussed comparatively with those reported in other lower vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218024
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  • 8
    Electronic Resource
    Electronic Resource
    Vascular permeability to lanthanum in the rat incisor pulp (1985)
    Springer
    Cell & tissue research 239 (1985), S. 131-136 
    Details
    ISSN: 1432-0878
    Keywords: Capillary permeability ; Lanthanum ; Peripheral nerves ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Experiments were performed to compare the permeability of capillaries supplying the endoneurial environment, which is invested by perineurium, with vascular permeability in the pulp where perineurium is absent. Anaesthetised rats were perfused through the aorta with physiological solutions containing lanthanum nitrate at 37° C. Pieces of inferior alveolar nerve and segments of mandibular incisors were immersion-fixed and transverse sections were examined electron microscopically for the distribution of lanthanum. In the pulp the nerve fibres pass between lanthanum-impermeable arterioles and venules en route to the incisal end. In the peripheral pulp a few capillaries were permeable but the most permeable capillaries lay between the odontoblasts. Pulpal capillary permeability was attributed to the fenestrated endothelium and contrasted with the unfenestrated endoneurial capillaries which were impermeable to lanthanum. Whereas the tight junctions of endoneurial capillaries are known to prevent certain blood-borne substances from entering the endoneurium, it was not clear whether the permeability of the pulpal capillaries, which are distant from the nerve fibres, could affect the nerve fibre environment. No extravasated lanthanum reached the pulpal nerve fibres suggesting that they are not affected. Technically it was not possible to examine the incisal third of the tooth where the situation could be different because the volume of the pulp decreases and capillaries lie closer to the nerve fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214912
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  • 9
    Electronic Resource
    Electronic Resource
    Stimulatory effect of follicle-stimulating hormone on rat Leydig cells (1985)
    Springer
    Cell & tissue research 239 (1985), S. 405-415 
    Details
    ISSN: 1432-0878
    Keywords: Testis ; Leydig cell ; FSH ; Morphometry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of FSH on the testicular interstitial tissue of immature hypophysectomized rats were studied by comparing morphological changes in Leydig cells with quantitative changes in interstitial tissue histology using morphometric analysis. Three groups of rats received subcutaneous injections of 0.5 ml saline vehicle or 10 μg rFSH or 20 ng oLH (equivalent to the amount of LH known to contaminate the FSH), twice daily for 7 days. Administration of FSH significantly increased testis weight and stimulated more advanced spermatogenesis compared to saline or LH. Morphometric analysis of testes of LH-treated rats showed a small but significant increase in total interstitial cell volume compared to saline treatment. FSH caused much greater increases in the total volume of interstitial tissue and interstitial cells than either saline or LH and significantly increased the total volume of interstitial fluid by comparison with the other groups. FSH but not saline or LH treatment resulted in a striking hypertrophy of Leydig cells, to produce cells ultrastructurally identical to Leydig cells from adults. Since the target tissue of FSH is the seminiferous epithelium, the observed effects on Leydig cells by FSH treatment suggest that the secretion of factors by the seminiferous tubules may mediate the maturation of Leydig cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218021
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  • 10
    Electronic Resource
    Electronic Resource
    Acetylcholinesterase activity in nerve endings of tails of Rana japonica and R. catesbeiana during metamorphosis (1985)
    Springer
    Cell & tissue research 239 (1985), S. 511-517 
    Details
    ISSN: 1432-0878
    Keywords: Nerve ending ; Tadpole tail ; Ultrastructure ; Acetylcholinesterase ; Metamorphosis ; Rana japonica ; R. catesbeiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In anuran tadpole tails, the myelinated motor nerve fibers branch in the myoseptum to innervate both red and white muscle fibers at, or near, their ends. There are no significant ultrastructural differences between the nerve endings of the two types of muscle fibers. Intense acetylcholinesterase reaction product was observed in synaptic clefts and junctional folds, as well as in transverse tubules. As metamorphosis proceeded, the junctional folds of the nerve endings disappeared, however, acetylcholinesterase reaction product was still observed in the synaptic clefts. As muscle fibers began to degenerate, nerve endings began to separate from them. However, after nerve endings were completely separated from the surfaces, degenerated muscle fibers, synaptic and cored vesicles were still well preserved although no acetylcholinesterase reaction product was found. It seems clear that the mechanism of the muscle degeneration in the tadpole tail during metamorphosis is not the result of the degeneration of its nerve endings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219229
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  • 11
    Electronic Resource
    Electronic Resource
    Nerve cells and synaptic connections in the intestinal nerve of the snail, Helix pomatia L. (1985)
    Springer
    Cell & tissue research 239 (1985), S. 611-620 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Intestinal nerve ; Ultrastructure ; Helix pomatia ; Horseradish peroxidase technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of nerve cells and the finestructural organization of synaptic contacts have been investigated in the intestinal nerve in the snail Helix pomatia. Three types of nerve cells, occurring singly or in groups, can be distinguished on the basis of the ultrastructure of their perikaryon and content of granules. The peripheral output of these nerve cells has been verified by retrograde CoCl2 and NiCl2 staining. Both axosomatic and axo-axonic specialized synaptic contacts occur in the intestinal nerve. Presynaptic elements of these synaptic contacts contain 100–120 nm granular vesicles or 120–200 nm neurosecretory-like granules. Following intracellular horseradish peroxidase (HRP) labelling of identified central neurons responsible for peripheral regulatory processes, several labelled axons running toward the periphery can be followed throughout the branches of the intestinal nerve. These labelled axon processes (either primary axon or small collaterals) form specialized synaptic contacts, inside the intestinal nerve, and are always in a postsynaptic position. The occurrence of peripheral axo-somatic and axo-axonic synapses provides a morphological basis for integrative processes taking place in the intestinal nerve (peripheral nervous system) of Helix pomatia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219239
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  • 12
    Electronic Resource
    Electronic Resource
    The ultrastructural and biosynthetic characteristics of steroidogenic cells in the gonad of Monopterus albus (Teleostei) during natural sex reversal (1985)
    Springer
    Cell & tissue research 239 (1985), S. 383-394 
    Details
    ISSN: 1432-0878
    Keywords: Steroid cell ; Ultrastructure ; Steroidogenesis ; Intersexual fish ; Monopterus albus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural and biosynthetic characteristics of the steroid cells in the gonad of Monopterus albus have been studied. Ultrastructural features related to steroidogenesis have been identified in the interstitial Leydig cells, Sertoli cells, granulosa cells and thecal cells, and are especially abundant in the Leydig cells during the mid-intersexual phase. Steroidogenic ultrastructures in the Sertoli cells develop only during the maturation of the spermatogenic cysts, whereas in the granulosa and thecal cells, these features become obvious only during the maturation of the large oocytes. EM evidence also suggests a nutritive function for the Sertoli cells and the granulosa cells. Results of in vitro steroidogenic studies, using either testosterone or progesterone as a precursor, show a predominant conversion to androstenedione and 5α-reduced compounds, and suggest a change in biosynthesis from 5α-reduced products to androstenedione during sex reversal. 11-Ketotestosterone (11KT) has been identified, but not 11 β-hydroxytestosterone. Production of 11 KT is high in the late intersexual and the male phases, but a lack of a marked variation in 11KT production between the early and the mid-intersexual phase suggests that this steroid is not a trigger for natural sex reversal in Monopterus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218019
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  • 13
    Electronic Resource
    Electronic Resource
    Demonstration of the granular layer and the fate of the hyaline layer during the development of a sea urchin (Lytechinus variegatus) (1985)
    Springer
    Cell & tissue research 239 (1985), S. 455-458 
    Details
    ISSN: 1432-0878
    Keywords: Development ; Sea urchin ; Hyaline layer ; Granular layer ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Employing electron-microscopic methods that help retain polyanionic materials, we describe the extracellular coverings of a sea urchin (Lytechinus variegatus) throughout ontogeny. The surface of the embryo is covered by a two-layered cuticle (commonly called the hyaline layer), which in turn is covered by a granular layer. The granular layer is retained after addition of alcian blue to the fixative solutions, and has not been previously described for any sea urchin. After hatching, the granular layer disappears, but the hyaline layer continues to cover most of the larval surface until settlement and metamorphosis. A few days before metamorphosis, the hyaline layer lining the vestibular invagination of the competent pluteus larva is replaced by a three-layered cuticle resembling that of the adult sea urchin. The hyaline layer covering the rest of the larva is evidently lost at metamorphosis during the involution of the general epidermis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218028
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  • 14
    Electronic Resource
    Electronic Resource
    Heterogeneity among macrophages cultured from mouse bone marrow (1985)
    Springer
    Cell & tissue research 239 (1985), S. 693-701 
    Details
    ISSN: 1432-0878
    Keywords: Macrophage ; Bone marrow culture ; Heterogeneity ; Ultrastructure ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of macrophages in culture from mouse bone marrow was followed for 14 days by light and electron microscopy, ultrastructural cytochemistry, and flow cytometric analysis. By 10 days greater than 97% of the cells in culture were mononuclear phagocytes, and by 12 days greater than 99% were identifiable as macrophages. Ultrastructurally, three subpopulations of mononuclear phagocytes were distinguished based on the appearance of cytoplasmic structures. Early in culture, cells containing large, membrane-bounded vesicles predominated. With increasing time in culture these cells were replaced to varying degrees first by cells that contained vesicles filled with relatively dense, osmiophilic material and, finally, by macrophages that contained granules of various sizes, shapes and staining densities. Cytochemical (peroxidase and acid phosphatase) and colloidal gold uptake studies at the ultrastructural level suggested that many, if not all, of these cytoplasmic structures arose by pinocytosis and subsequent fusion of pinocytic vesicles with lysosomes. Analysis of DNA content of propidium iodide-stained nuclei by flow cytometry, coupled with the examination of cells treated with colchicine to arrest mitosis in metaphase, suggested that cell cycling was a negligible contributor to heterogeneity within cultured populations. Thus, by waiting until 12–14 days after bone marrow cultures were initiated, with partial replenishment of the culture medium at 7 days, heterogeneity could be greatly reduced in cultured macrophage populations. Taking this fact into consideration could help to reduce the variability seen in functional studies of macrophage populations that are less homogeneous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219251
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  • 15
    Electronic Resource
    Electronic Resource
    Organization of lymphoid tissue in the tonsilla lingualis (1985)
    Springer
    Cell & tissue research 240 (1985), S. 233-242 
    Details
    ISSN: 1432-0878
    Keywords: Lymphoid tissue ; Tonsilla lingualis ; Ultrastructure ; B- and T-lymphocytes ; Macaca fascicularis (Primates, Cercopithecoidea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Lymphoid organs are highly organized structures made up of different tissue compartments, each with its own specific cell populations. However, the cellular elements of the lingual tonsil, which forms a significant part of Waldeyer's pharyngeal ring, are not yet documented. This study, therefore, describes the fine structure and tissue organization of tonsilla lingualis in Macaca fascicularis. Ten selected crypto-lymphatic units originating from five perfusion-fixed animals were analysed ultrastructurally. Based on the fine-structural elements contained within, the lymphoid tissue of tonsillar units could be subdivided into follicular (germinal centre) and parafollicular areas. The latter contained predominantly small lymphocytes, lymphoblasts resembling T-blasts, plasma cells, macrophages, occasional neutrophils and many reticular cells resembling fibroblasts. A distinct feature of the parafollicular area was the presence of numerous high endothelial (HEV)or postcapillary venules (PCV). The follicular areas contained many small and large lymphoid cells, mitotic cells, plasmablasts, macrophages and specialised reticular cells resembling follicular dendritic cells (FDC) with distinct desmosomal junctions. These observations show that the crypto-lymphatic units of the lingual tonsil are, in fact, organised into distinct B- and T-cell compartments with their own specific lymphoid and accessory cells.
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    URL: http://dx.doi.org/10.1007/BF00217579
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  • 16
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    Architecture of associations of minor salivary gland ducts and lymphoid follicles in Macaca fascicularis (1985)
    Springer
    Cell & tissue research 240 (1985), S. 223-232 
    Details
    ISSN: 1432-0878
    Keywords: Oral mucosa, simian ; Local mucosal immunity ; Minor salivary glands ; Duct/lymphoid follicle assemblies ; Ultrastructure ; Macaca fascicularis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous light-microscopic and ultra-immunohistochemical tracer studies revealed the existence of an independent local immune response of the simian oral mucosa. This local response is attributed to the presence of minor salivary gland (MSG) duct-related lymphoid tissue. Semithin sections from a total of 263 Epon-embedded tissue blocks from the labial and buccal mucosae of seven monkeys, Macaca fascicularis, were analysed light-microscopically, and 10 suitable MSG duct/follicle assemblies were investigated ultrastructurally. These duct/follicle assemblies include follicular and parafollicular compartments with distinct fine-structural elements. The follicular area or germinal centre contains numerous small and large lymphoid cells, mitotic figures, plasmablasts, macrophages, and cells resembling the follicular dendritic cells with distinct desmosomal junctions. The parafollicular area, which includes the heavily infiltrated duct wall, contains numerous small lymphocytes, T-lymphoblasts, plasma cells and reticular cells resembling fibroblasts. A distinct feature of this compartment is the presence of high endothelial venules (HEV). The presence of HEV and numerous blast cells, resembling blast-forming T-lymphocytes activated in vitro, in a specific area of the duct/follicle assembly strongly suggests that this area is structurally and physiologically identical to the thymus-dependent area of other lymphoid tissues. In other words, the duct/follicle assemblies of simian MSG contain the various specific fine-structural elements that are suitable for antigen recognition and processing. These elements are distributed in discrete compartments comparable to the B- and T-cell areas of “classical” lymphoid tissue.
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    URL: http://dx.doi.org/10.1007/BF00217578
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of brief vascular perfusion on the ultrastructure and activity of mitochondria isolated from the rat heart (1985)
    Springer
    Cell & tissue research 240 (1985), S. 247-249 
    Details
    ISSN: 1432-0878
    Keywords: Heart ; Mitochondria ; Perfusion ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Mitochondria isolated from heart tissue after a 1-min perfusion with Hanks medium were found to have significantly lower rates of State-3 respiration and respiratory control ratios compared to mitochondria isolated from non-perfused hearts. Examination of the mitochondrial preparations by electron microscopy revealed that a large proportion of the mitochondria isolated from perfused heart tissue were swollen and broken compared to mitochondria from non-perfused hearts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217581
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  • 18
    Electronic Resource
    Electronic Resource
    A cytochemical study of myeloid bodies in the retinal pigment epithelium of the newt Notophthalmus viridescens (1985)
    Springer
    Cell & tissue research 240 (1985), S. 641-648 
    Details
    ISSN: 1432-0878
    Keywords: Retinal pigment epithelium ; Myeloid bodies ; Ultrastructure ; Lipid metabolism ; Endoplasmic reticulum ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It has been suggested (Yorke and Dickson 1984) that myeloid bodies (MBs) in the retinal pigment epithelium (RPE) of the newt, Notophthalmus viridescens, may represent areas of endoplasmic reticulum where lipids, such as 11-cis retinal derived from phagocytized outer segment tips, accumulate prior to esterification. Experiments in which an artificial ester substrate was added during in-vitro incubations have shown that esterase activity is represented in all areas of the newt RPE endoplasmic reticulum, including sites adjacent to all MBs. In related tests in which the localization of enzyme activity was restricted to areas of the cell where there had been accumulations of naturally-occurring (endogenous) esters, the products of ester hydrolysis were restricted to profiles of endoplasmic reticulum associated with lipid droplets, and with the interior of about 20% of those MBs that appeared completely circular in sections. This enzyme activity was not associated with other MB configurations. Results from endogenous-ester hydrolysis were identical to those obtained after staining with ZIO. This ZIO-reactivity was not affected by pre-incubation with agents that blocked or protected sulphydryl groups, and ZIO-reactive sites associated with MBs did not form complexes with digitonin. These observations suggest that MBs are a site of lipid-ester formation, but that they do not represent unique intracellular areas for this activity.
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    URL: http://dx.doi.org/10.1007/BF00216352
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  • 19
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    Ultrastructural and immunohistochemical studies on non-ciliated cells of the tracheal epithelium of normal, phenobarbital-treated, and 3-methylcholanthrene-treated mice (1985)
    Springer
    Cell & tissue research 240 (1985), S. 501-504 
    Details
    ISSN: 1432-0878
    Keywords: Non-ciliated tracheal cell ; Smooth endoplasmic reticulum ; Ultrastructure ; Cytochrome P-450 ; Immunohistochemistry ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Non-ciliated SER-rich cells of the tracheal epithelium of normal, phenobarbital-treated and 3-methylcholanthrene-treated mice were studied ultrastructurally and immunohistochemically. The apical portion of these cells protrudes into the tracheal lumen, especially in the mice treated with the two compounds, and the apical cytoplasm is filled with numerous tubular elements of SER. Besides, the non-ciliated cells of 3-methylcholanthrene-treated mice show a strong positive reaction to the antiserum against microsomal cytochrome P-450 of liver. These findings support the concept that the non-ciliated tracheal cell may be involved in the metabolism of endogeneous and exogeneous chemical compounds.
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    URL: http://dx.doi.org/10.1007/BF00222368
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  • 20
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    Electron-microscopic study of the collagen fibrils of the rat tail tendon as revealed by freeze-fracture and freeze-etching techniques (1985)
    Springer
    Cell & tissue research 240 (1985), S. 529-534 
    Details
    ISSN: 1432-0878
    Keywords: Collagen fibril ; Freeze-fracture ; Tail tendon ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the collagen of rat tail tendon was investigated by the freeze-fracture technique. Collagen fibers were pretreated with the digestive enzymes, α-amylase, elastase and collagenase to remove matrix substances. Some of the samples were etched for 20 min. Fibrils had an average diameter of 318±12 nm and a banded structure with a mean periodicity of 64.2±0.9 mm; the banding was most marked in α-amylase/elastase-treated specimens, although the periodicity was independent of pretreatment. Microfibrils were well-displayed following α-amylase/elastase and collagenase pretreatments. A difference in the diameters of microfibrils was, however, observed between etched specimens (8.3±0.3 nm) and those prepared by other experimental methods (11.4±0.5 nm). In replicas of collagenase-treated and etched specimens, the interconnecting filaments in the interfibrillar region formed a network that was continuous with the microfibrils of collagen fibrils. The diameter of the interconnecting filaments was the same as that of microfibrils. Microfibrillar bundles were observed in the interfibrillar region.
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    URL: http://dx.doi.org/10.1007/BF00216341
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  • 21
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    Functional differences between two structurally distinct types of steroidogenic cell in the avian adrenal gland (1985)
    Springer
    Cell & tissue research 240 (1985), S. 561-567 
    Details
    ISSN: 1432-0878
    Keywords: ACTH ; Adrenal zonation ; Birds ; Corticosterone ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary There are two regions of steroidogenic cells in the duck adrenal gland. An outer, subcapsular zone (SCZ), consisting of cells with irregularly shaped nuclei, shows relatively little smooth endoplasmic reticulum and mitochondria with shelf-like cristae. This region surrounds the inner zone (IZ) of the gland which is comprised of smaller cells with rounded nuclei, a more abundant smooth endoplasmic reticulum and mitochondria with tubular cristae. When samples of tissue from these distinct regions of the gland are superfused in vitro with media containing concentrations of 1–24 ACTH ranging from 100 to 1000 ng per ml (0.034 to 0.34 μM) the steroidogenic cells in both zones release corticosterone in a dose-dependent manner. The dose-responsiveness of both the SCZ and the IZ cells over this range is a complex quadratic function of the 1–24 ACTH concentration in the medium and the semilogarithmic linear portions of the dose-response curves are restricted to a narrow midrange of ACTH concentrations. Throughout the dose-response range, however, the steroidogenic cells of the IZ are more responsive to corticotropic stimulation than are the cells of the SCZ. The cells of the two zones are further distinguished by their responses to a challenge for a second time with medium containing 1–24 ACTH; the responses of the IZ cells to a second challenge were greater than those of the SCZ cells, and at a high concentration of ACTH the SCZ slices showed no significant second response.
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    URL: http://dx.doi.org/10.1007/BF00216345
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  • 22
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    Differentiation of the rat epididymis after withdrawal of androgen (1985)
    Springer
    Cell & tissue research 241 (1985), S. 657-662 
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    ISSN: 1432-0878
    Keywords: Epididymis ; Differentiation ; Organ culture ; Castration ; Ultrastructure ; Morphometry ; Cell types ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The differentiation capacity of the rat epididymis after depletion of androgen was studied in organ culture and in castrated rats. The differentiation of ‘narrow cells’ in 5- and 10-day-old explants and in 10-day-old castrated rats suggests that: (i) the testicular androgens are not essential for their differentiation, (ii) a differential androgen dependence exists among the epididymal cell types, (iii) the undifferentiated epithelial cells are the precursors of the narrow cells.
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    URL: http://dx.doi.org/10.1007/BF00214588
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  • 23
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    Focal regeneration in the rat myocardium following cold injury (1985)
    Springer
    Cell & tissue research 241 (1985), S. 459-463 
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    ISSN: 1432-0878
    Keywords: Myocardium ; Regeneration ; Ultrastructure ; Cold injury ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sequential cytological events in the myocardium of the rat were followed for 3 weeks after cold injury by light and electron microscopy. The traumatized area was initially filled with leukocytes and undifferentiated mononucleated cells and subsequently mainly with fibroblasts surrounded by collagen fibers. However, in the margins of the necrotic area repair processes of damaged myocardial cells and probably also the appearance of newly formed cells were evident. The ultrastructural features of these cells were characterized by clusters of ribosomes, numerous mitochondria that were dispersed in the cytoplasm and formation of junctional complexes and transverse tubular systems. Fibrillogenesis was also clearly evident in these cardiomyocytes. The myofibrillar material was initially dispersed in the cytoplasm and associated with clusters of ribosomes and thereafter with presumptive Z-bands and intercalated discs. The myofibrils became further organized in the shape and orientation of those of mature cells two to three weeks after injury. It is concluded that following cold injury regeneration in the mammalian myocardium takes place but is limited to the perinecrotic area. The process resembles the sequential cytological events which occur in cardiomyocytes during embryonic and postnatal development of the ventricular myocardium.
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    URL: http://dx.doi.org/10.1007/BF00217194
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  • 24
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    The effect of clomiphene citrate on blastocyst development and implantation in the rabbit (1985)
    Springer
    Cell & tissue research 241 (1985), S. 495-503 
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    ISSN: 1432-0878
    Keywords: Embryo transfer ; Ultrastructure ; Implantation ; Clomiphene citrate, effects ; Blastocyst, development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The induction of ovulation with clomiphene citrate (CC) in human patients results in a high ovulation rate but achieves a relatively low pregnancy rate. To clarify the possible role of CC in interfering with the normal reproductive physiology and embryology, we have used our rabbit model and transferred 4-day-old blastocysts from untreated donors to CC-treated pseudopregnant recipients and from CC-treated donors to untreated pseudopregnant recipients to study embryonic development and implantation. Each group was further subdivided into two subgroups, one receiving CC before and the other after ovulation. CC was administered subcutaneously in three consecutive doses of 10 mg/kg body weight. Ovulation was induced with pregnant mare serum gonadotropin (PMS) and human chorionic gonadotropin (hCG). The implantation rate of the control group, evaluated on day 8 of pregnancy, reached 62.0%. When recipients were treated with CC before ovulation, implantation rate was reduced to 18.8% (P 〈 0.0002), and to 20.0% (P 〈 0.003) when CC was administered after ovulation. The implantation rate of blastocysts transferred from donors, treated before ovulation, is 22.2% (P 〈 0.0055), however, reached 70.8% when treatment was started after ovulation. All implantations were analysed microscopically and showed normal morphological features. Our results demonstrate a potential multiple effect of CC, first on the endometrium by altering its receptivity for the implanting conceptus, second, on tubal physiology by altering egg transport, and finally on ovum maturation before ovulation interfering with development of blastocysts. These parameters may all result in rapid decrease in establishment of implantations and in turn in very low pregnancy rates.
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    URL: http://dx.doi.org/10.1007/BF00214568
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    Ultrastructure of the luminescent system of the ctenophore Mnemiopsis leidyi (1985)
    Springer
    Cell & tissue research 242 (1985), S. 333-340 
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    ISSN: 1432-0878
    Keywords: Bioluminescence ; Ctenophore ; Mnemiopsis leidyi ; Photocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The photocytes and other endodermal cells composing the wall of the meridional canals of the comb-jelly, Mnemiopsis leidyi, were investigated by transmission electron microscopy. Although many of these cells possess distinctive features such as a ciliary apparatus, lysosome-like bodies or vacuoles, they share with photocytes the presence of a network of rough endoplasmic reticulum (RER) whose cisternae enwrap large mitochondria and are aligned along the subsurface of the plasma membrane. A stereological analysis of organelle content in photocytes confirms the prominence of the RER in these cells and a shift of RER from mitochondria to plasma membrane subsurface in photocytes induced to luminesce by the mitochondrial inhibitor dinitrophenol. Photocytes and other endodermal cells of the meridional canals are interconnected by numerous gap junctions which, among photocytes, often form symmetrical triads with cortical cisternae and mitochondria. The gap junctions and RER/mitochondria assemblages are interpreted as possible substrates for, respectively, conduction of luminescence excitation along the canals and for excitation-luminescence coupling. Neuntes occasionally make synapses with photocytes and other endodermal cells lying adjacent to the mesoglea.
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    URL: http://dx.doi.org/10.1007/BF00214545
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    A microscopic investigation of enamel in wombat (Vombatus ursinus) (1985)
    Springer
    Cell & tissue research 242 (1985), S. 349-355 
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    ISSN: 1432-0878
    Keywords: Teeth (Vombatus ursinus) ; Enamel (regions) ; Ultrastructure ; Enamel (mature and developing)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the enamel of continuously growing Vombatus ursinus molars was carried out using the techniques of light microscopy, hardness testing, scanning electron microscopy and transmission electron microscopy. From the erupted end to within 8 mm of the growing end, mature enamel was observed and it was found that between comparable areas there were no significant ultrastructural differences in enamel; however, small (∼12nm diameter), loosely packed needle-like crystals characteristic of developing enamel were observed near the growing end. Mature enamel was found to consist of three optically-translucent regions interleaved with two opaque regions. Opaque enamel was softer than translucent enamel. The opacity and relative softness characteristic of two of the enamel regions was not related to prism pattern or orientation; it was, however, related to the presence of voids (∼28 nm diameter) in these regions.
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    URL: http://dx.doi.org/10.1007/BF00214547
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  • 27
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    Quantitative analysis of estradiol-17β-induced changes in the ultrastructure of the liver of the male zebrafish, Brachydanio rerio (1985)
    Springer
    Cell & tissue research 242 (1985), S. 377-382 
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    ISSN: 1432-0878
    Keywords: Liver ; Hepatocytes ; Ultrastructure ; Estradiol ; Vitellogenesis ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hepatocytes of male zebrafish, Brachydanio rerio, were studied by means of light- and electron-microscopy, following a period of maximally 16 days of in-vivo treatment with estradiol-17β. The responsiveness of the male hepatocytes to this female sex steroid was investigated by use of morphometric methods. The results of this investigation show that the responsiveness was most obvious between 2 and 16 days, as revealed by an increase in cell size, accompanied by a proliferation of the granular endoplasmic reticulum and the Golgi complex. In addition, accumulations of glycogen granules, which are characteristic of hepatocytes in untreated males, had disappeared and lipid droplets had accumulated. These experimentally induced changes in the morphology of the male hepatocyte closely resemble those described for the female hepatocyte during the sexual cycle. It is concluded that the hepatocytes of male zebrafish can be stimulated by estradiol-17β to produce vitellogenin and that in female zebrafish this steroid is a key sex hormone responsible for vitellogenin production by the liver during the natural sexual cycle.
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    URL: http://dx.doi.org/10.1007/BF00214551
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  • 28
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    Three-day continuous drainage of pancreatic juice in the cortisone-treated conscious rat: Analysis of enzyme activities and ultrastructural changes (1985)
    Springer
    Cell & tissue research 242 (1985), S. 191-196 
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    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Rat ; Cortisone ; Ultrastructure ; Enzyme secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have investigated the short-term effects of hydrocortisone (60 mg/kg per day) and placebo on basal and stimulated pancreatic secretion in the conscious rat. Volume and enzyme secretion were determined; fine structural changes were examined simultaneously. The pancreatic and bile ducts were cannulated separately; pancreatic juice was drained via an isolated fistula, and bile was recirculated into the duodenum. The application of hydrocortisone led to an almost complete inhibition of the secretory response of the exocrine pancreas when stimulated with 0.25 U secretin in combination with 5 × 10-8 g caerulein per h. It strongly affected the secretion rates of volume, protein, lipase, chymotrypsin, trypsin and carboxypeptidase, whereas the secretion rate of alpha-amylase continued to show a slight increase after stimulation. After stimulation with secretin and caerulein, the hydrocortisone-treated animals showed a higher density of zymogen granules in the acinar cell and an increase in the number of autophagic vacuoles in comparison to the equally stimulated placebo-treated rats. It is concluded that the short-term inhibition of pancreatic secretion by hydrocortisone occurs largely as a result of an inhibition of cellular enzyme discharge.
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    URL: http://dx.doi.org/10.1007/BF00225576
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    Effects of colchicine on the ultrastructure of mouse taste buds (1985)
    Springer
    Cell & tissue research 242 (1985), S. 409-416 
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    ISSN: 1432-0878
    Keywords: Taste bud ; Colchicine ; Ultrastructure ; Microtubules ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Effect of colchicine on the ultrastructure of taste bud cells was studied in the mouse. In untreated mice microtubules were abundant throughout the entire cytoplasm of type-III cells, but only in the apical cytoplasm of type-I cells. After 2 h of colchicine treatment, no microtubules were observed in any taste bud cells; dense secretory granules in the apical cytoplasm of type-I cells mostly disappeared, and instead, numerous phagosomes appeared. It is suggested that colchicine causes an interruption of the transport of the secretory granules in type-I cells from the Golgi apparatus to the membrane of the apical surface, from which release occurs. In type-III cells, after 4 or 5 h of treatment, dense-cored vesicles scattered throughout the cytoplasm tended to increase in number; they were often observed to accumulate in the vicinity of the Golgi apparatus. Five hours after treatment with 5-hydroxy-l-tryptophan (5-HTP) following colchicine pretreatment, monoamine specific fluorescent cells and vesicles with highly electron-dense cores of type-III cells were still present. On the other hand, 5 h after 5-HTP treatment alone both fluorescent cells and vesicles with highly electron-dense cores had already disappeared. These observations suggest that the treatment with colchicine interrupts the transport of densecored vesicles of type-III cells to synaptic areas, in which those vesicles are presumed to discharge the neurotransmitter substance.
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    Characterization of dendritic cells, isolated from normal and stimulated lymph nodes of the rat (1985)
    Springer
    Cell & tissue research 242 (1985), S. 469-474 
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    ISSN: 1432-0878
    Keywords: Lymph node ; Antigen stimulation ; Dendritic cells ; Enzyme- and immunocytochemistry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Non-lymphoid dendritic cells were isolated from normal and paratyphoid vaccine-stimulated lymph nodes draining the rat skin. They were studied using enzymecytochemical, immunocytochemical and electron-microscopical methods. These cells had an irregular outline and an eccentrically situated nucleus. All showed acid phosphatase activity in a central area and expressed Ia antigen on the plasma membrane. Birbeck granules were exclusively present in dendritic cells isolated from lymph nodes in the induction phase of the immune response. This observation concurs with the presence of Birbeck granules in interdigitating cells in situ during the same period of the immune response. It is concluded that the dendritic cells are the in-vitro equivalents of the non-actively phagocytizing population of interdigitating cells.
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    URL: http://dx.doi.org/10.1007/BF00225411
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    Reversibility of omeprazole-evoked changes in the ultrastructure of ECL cells in the rat stomach (1997)
    Springer
    Cell & tissue research 291 (1997), S. 91-95 
    Details
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Omeprazole ; Granules/vesicles ; Ultrastructure ; Stomach ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The ECL cells are histamine- and peptide hormone-producing endocrine cells in the rat oxyntic mucosa. They are rich in secretory vesicles and also contain microvesicles and electron-dense granules. They operate under the control of circulating gastrin. In the present study, we examined the ECL-cell ultrastructure after long term treatment with omeprazole, which is known to induce hypergastrinemia, and after withdrawal of the drug. Rats received omeprazole (400 µmol/kg per day, orally) for 16 days and were killed 1, 5, 20, or 40 days after the last dose of the drug. Oxyntic mucosal specimens were processed for electron microscopy. Electron micrographs of ECL-cell profiles were analyzed planimetrically. The ECL-cell profile area increased promptly in response to omeprazole, the secretory vesicles and granules were reduced in number and volume density, the microvesicles were unchanged in number but reduced in volume density, and vacuoles appeared. Within a week after stopping the omeprazole treatment, the numbers and volume densities of secretory vesicles and microvesicles returned to pre-stimulation values. Also, the vacuoles disappeared promptly. The ECL-cell profile area decreased below the pre-stimulation level within five days after stopping treatment, while, in contrast, the granules increased in number and volume density. Somewhat surprisingly, the cell size and the granule compartment did not return to normal until 40 days after stopping treatment.
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    Exocytosis in the antral gastrin cells of mouse, rat, and guinea pig after stimulation by carbamylcholine (1997)
    Springer
    Cell & tissue research 289 (1997), S. 463-472 
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    ISSN: 1432-0878
    Keywords: Key words: Exocytosis ; Endocytosis ; Gastrin cells ; Carbamylcholine ; Ultrastructure ; Pyloric antrum ; Guinea pig (Hartley) ; Mouse (ICR) ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In order to capture the exocytotic figures of gastrin cells in the pyloric antrum of the stomach, we examined antral cells of the mouse, rat, and guinea pig by electron microscopy following stimulation with the cholinergic secretagogue carbamylcholine. Increased numbers of omega profiles indicative of exocytosis were seen in the basal or lateral cell membrane after stimulation with carbamylcholine. The number of exocytotic figures in stimulated gastrin cells was higher in the guinea pig than in the mouse and rat. Coated and non-coated omega profiles and coated pits in the plasma membrane were smaller than the secretory granules. Omega profiles with or without electron-dense contents were seen. Coated and non-coated vesicles were often visible near the plasma membrane of stimulated gastrin cells in all three species, large cytoplasmic vacuoles also being found in the guinea pig. In the mouse pretreated with horseradish peroxidase, reaction deposits were observed in the omega profiles and in microvesicles near the plasma membrane. These results suggest that, after exocytosis, membrane retrieval and endocytosis occur in the gastrin cells.
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    Development of striated rootlets during ciliogenesis in the human oviduct epithelium (1997)
    Springer
    Cell & tissue research 290 (1997), S. 39-42 
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    ISSN: 1432-0878
    Keywords: Key words: Ciliogenesis ; Striated rootlets ; Oviduct ; Ciliated cells ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Striated rootlets in ciliated cells are conical banded structures composed of longitudinally aligned filaments. The formation of striated rootlets during ciliognesis in the human oviduct epithelium was studied by electron microscopy. Primitive rootlets appeared at the proximal side of basal bodies before or at the same time as ciliary budding. After the formation of several striations, the tip of the rootlets extended deeply toward the interior of the cell and became differentiated into two distinct parts, viz., the proximal conical part connected to the basal body and the distal fibrillar part. The periodicity of the striations in the fibrillar part was 68.5±2.95 nm, about 5 nm longer than that of the conical part (63.9±2.25 nm). The dark band in the striation was thicker in the fibrillar part than in the conical part. Since the fibrillar part was not observed in the mature cilium, this part was considered as being either degraded or changed into the conical part during ciliogenesis.
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    Morphometry of muscle fibre types in the carp (Cyprinus carpio L.) (1985)
    Springer
    Cell & tissue research 241 (1985), S. 193-201 
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    ISSN: 1432-0878
    Keywords: Fish ; Muscle fibre types ; Ultrastructure ; Morphometry ; Twitch characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural parameters of muscle fibre types of the carp (Cyprinus carpio L.) were measured and compared with their contractile properties. In red fibres, which are slower than pink fibres, the relative length of the junction between the T system and the sarcoplasmic reticulum (T-SR junction) is smaller and the Z lines are thicker than in pink fibres. Pink fibres have a smaller relative length of T-SR junction than white fibres from the axial muscles. The two types of red fibres present in carp muscle also differ in their relative lengths of T-SR junction. Significant differences in the relative areas of the SR were not found. The relative volume of myofibrils in red fibres is two-thirds that in pink fibres, a difference that is not reflected in the maximal isometric tetanic tensions of these types. Red fibres, which are less easily fatigued than pink fibres, have larger relative volumes of subsarcolemmal and intermyofibrillar mitochondria. Small pink fibres have a larger relative volume of subsarcolemmal mitochondria than large pink fibres, but have a similar relative volume of intermyofibrillar mitochondria. Small and large pink fibres differ in the relative volumes of their membrane systems, but have similar relative lengths of T-SR junction.
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    Structure of tendon organs of the rat after neonatal de-efferentation (1985)
    Springer
    Cell & tissue research 241 (1985), S. 229-236 
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    ISSN: 1432-0878
    Keywords: Tendon organs, rat ; Neonatal de-efferentation ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The number, size and structure of tendon organs were examined in leg muscles of the rat 3–19 weeks after de-efferentation performed in newborn animals by removal of the lumbosacral spinal cord. After this operation, tendon organs differentiated and grew in disused muscles and were innervated by primary sensory neurons, the dorsal roots of which had been disrupted. Three weeks after de-efferentation extensor digitorum longus muscles contained 14.1±1.0 (mean±standard error) and soleus muscles had 14.2±1.6 tendon organs, which corresponds to the mean number of tendon organs in the respective control muscles. The mean size of tendon organs was, however, changed. Tendon organs became on the average by 53% longer and by 35% thinner in de-efferented extensor digitorum longus muscles that were prolonged due to immobilization, as compared with shorter and wider tendon organs in de-efferented soleus muscle that remained in the shortened position. The ultrastructural differentiation of tendon organs was completed after the operation as under normal conditions. Thus it can be concluded that elimination of muscle function during the period of postnatal development indirectly affects the mean size of these receptors, but does not otherwise interfere with their morphogenesis.
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    Ultrastructural autoradiographic localization of serotonin in the pituitary of a teleost fish, Poecilia latipinna (1985)
    Springer
    Cell & tissue research 240 (1985), S. 489-492 
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    ISSN: 1432-0878
    Keywords: Serotonin ; Pituitary ; Autoradiography ; Ultrastructure ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light- and electron-microscopic autoradiographic studies of pituitaries of the molly Poecilia latipinna, after their incubation with tritiated serotonin, revealed the presence of labelled cells in the proximal pars distalis, together with cell processes or nerve fibres throughout all regions of the gland except the prolactin cell zone. The serotonincon-centrating cells and most of the fibres contained small dense-cored vesicles, but some labelled fibres contained larger granules similar in ultrastructure to those of vasotocinergic fibres.
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    URL: http://dx.doi.org/10.1007/BF00222365
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    Ultrastructural changes associated with K+-evoked peptide secretion from a neurohemal organ of the crab, Cardisoma carnifex (1985)
    Springer
    Cell & tissue research 242 (1985), S. 67-73 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Ultrastructure ; Potassium stimulation ; Crustacea ; Hormone release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscopic comparison of K+-stimulated and unstimulated crab sinus glands reveals significant differences in neurosecretory terminal morphology. Sinus glands exposed to elevated K+ saline for increasing periods of time show increasing numbers of exocytotic release profiles, vacuoles, and multilamellate bodies, and a decrease in the number of microvesicles within 10 μm of release sites. These morphological changes are well correlated with secretion of red-pigment-concentrating hormone, as determined by bioassay of perfusate from the individual preparations.
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    URL: http://dx.doi.org/10.1007/BF00225564
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    Lamellar to tubular conformational changes in the endoplasmic reticulum of the retinal pigment epithelium of the newt, Notophthalmus viridescens (1985)
    Springer
    Cell & tissue research 241 (1985), S. 629-637 
    Details
    ISSN: 1432-0878
    Keywords: Retinal pigment epithelium ; Ultrastructure ; Endoplasmic reticulum ; Lipid phase transitions ; Metamorphic mosaic model ; Myeloid bodies ; Urodeles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The retinal pigment epithelium (RPE) of the newt (Notophthalmus viridescens) was examined ultrastructurally under both in-vivo and in-vitro conditions. Five distinct conformations of smooth endoplasmic reticulum (SER), two lamellar and three tubular, were observed. The two lamellar conformations included myeloid bodies, which have previously been described (Yorke and Dickson 1984), and fenestrated SER. The latter appeared as layers of flattened or curved cisternae which were penetrated by fenestrations. Fenestrated SER became indistinguishable from the highly branched and convoluted random-tubular SER through the formation of an intermediate configuration (“tubular sheets”). The remaining tubular SER conformations appeared to arise from random-tubular SER through a progressive reduction in branching and a straightening of individual tubules. Fascicular SER was represented by the hexagonal organization of straight, unbranched tubules into bundles (fascicles). Spiral SER consisted of a similar hexagonal arrangement, but the unbranched tubules spiralled about one another. Neighbouring tubules in areas of spiral SER were also joined together by pairs of electrondense bars. Although lamellar (especially myeloid bodies) and random-tubular configurations of the SER were common features in vivo, fascicular and spiral SER were primarily conformations encountered in vitro. Conditions favouring bilayer lipid phases also appear to facilitate the formation of both myeloid bodies and fascicular SER. These conditions included increased duration of incubation, low (〈20° C) incubation temperatures, and Ca2+-free incubations with EGTA. Random-tubular SER was most prevalent in media supplemented with fetal calf serum and also after warmer (30° C) incubation temperatures. We speculate that the different conformations of SER observed in the newt RPE may be due, in part, to lipid phase transitions within the membranes of this organelle. However, the specific formation of fascicular and spiral SER may also involve some additional factor, possibly a protein.
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    URL: http://dx.doi.org/10.1007/BF00214585
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    Heart structure and ventricular ultrastructure of hemoglobin- and myoglobin-free icefish Channichthys rhinoceratus (1985)
    Springer
    Cell & tissue research 242 (1985), S. 669-676 
    Details
    ISSN: 1432-0878
    Keywords: Heart ; Myocardium ; Ultrastructure ; Antarctic fish ; Icefish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structural and ultrastructural characteristics of the heart of Channichthys rhinoceratus, an antarctic teleost devoid of respiratory pigments, are described and compared with those obtained from the red-blooded related species Notothenia rossii. The heart of the icefish is characterized by a spongy myocardium supplied with a highly developed arterial coronary system. This vasculature includes a subepicardial system and an extensive intratrabecular capillary network. Arterial hilar network and Thebesian vessels may also be present. The bulbus arteriosus shows unusually large spheroid structures located in the middle layer of the wall. Both white- and red-blooded species display comparable myocardial cell morphology and organelle distribution. However, the mitochondrial cristae of the former are more densely packed and the sarcolemma possesses numerous caveolae. A large proportion of non-contractile cells is also found in the icefish ventricular wall.
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    URL: http://dx.doi.org/10.1007/BF00225436
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    Platelet/endothelial cell adhesion molecule-1 (PECAM-1) is localized over the entire plasma membrane of endothelial cells (1997)
    Springer
    Cell & tissue research 290 (1997), S. 623-631 
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    ISSN: 1432-0878
    Keywords: Key words: PECAM-1 (platelet/endothelial cell adhesion molecule-1) ; Endothelium ; HUVEC (human umbilical vein endothelial cells) ; Myocardium ; Ultrastructure ; Human ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The subcellular localization of PECAM-1 in endothelial cells was examined by using advanced morphological techniques, such as confocal scanning microscopy and immunolabeling procedures for electron microscopy. The localization of PECAM-1 was studied immunohistochemically with five specific monoclonal antibodies and one polyclonal antibody (all anti-human) in human and rabbit myocardium and in isolated endothelial cells. In vivo, PECAM-1 was localized uniformly on the plasma membrane of all vascular endothelial cells, predominantly on the luminal side of vessels. No specific increase in labeling was found at sites of cell-to-cell contact. In vitro, primary isolated cells (human umbilical vein endothelial cells) showed continuous labeling of the entire cell membrane. Cells of higher passages were labeled in a manner similar to freshly isolated cells. Our findings refute the commonly accepted hypothesis that PECAM-1 is localized only at cell-to-cell contacts. Further, we have not been able to confirm the hypothesis regarding the important mechanical role of PECAM-1 in stabilizing the endothelial monolayer. Since PECAM-1 is also expressed on platelets and is known to bind to itself, the way in which PECAM-1-positive endothelial cells are protected against binding of PECAM-1-positive platelets remains unclear. In view of these findings, the role of PECAM-1 in the leukocyte migration cascade needs to be re-evaluated.
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    URL: http://dx.doi.org/10.1007/s004410050968
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    The peroxisomes of the hepatopancreas in two species of chitons (1997)
    Springer
    Cell & tissue research 290 (1997), S. 655-664 
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    ISSN: 1432-0878
    Keywords: Key words: Peroxisomes ; Ultrastructure ; Digestive gland ; Acanthochiton crinita ; Lepidochitona cinerea (Mollusca ; Polyplacophora)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract . This paper presents the first description of peroxisomes in polyplacophorans. As in other molluscs, the hepatopancreas of chitons is composed of basophilic and digestive cells. In the basophilic cells, the endoplasmic reticulum is abundant and several Golgi stacks can be observed. These cells also possess secretion granules and vacuoles with spherites. The digestive cells are mainly characterized by the presence of many food vacuoles. Several peroxisomes were observed in the basophilic cells of Acanthochiton crinita, most of them almost spherical. The matrix is filled with tubular structures and a crystalline nucleoid is also present in these organelles. In the digestive cells of A. crinita, peroxisomes are also almost spherical and possess two kinds of nucleoids. One of them presents a diamond shape and a bundle of tubular structures forms a second kind of nucleoid, which shows an elongated form. In Lepidochitona cinerea, the peroxisomes of basophilic cells are spherical or oval. Within the matrix, a cluster of dense rods and a prismatic nucleoid were observed. In the digestive cells of this species, almost spherical or oval peroxisomes are common, but they are smaller than the peroxisomes of the preceding cells. Nucleoids were not detected, but a few dense rods could be observed in the matrix. In both cell types of the two species, catalase activity was detected in the peroxisomal matrix. In addition, the elongated nucleoid of A. crinita digestive-cell peroxisomes and the nucleoid of L. cinerea basophilic-cell peroxisomes also present catalase activity.
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    URL: http://dx.doi.org/10.1007/s004410050971
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    Mucosal surface area in chicken small intestine during development (1997)
    Springer
    Cell & tissue research 290 (1997), S. 71-78 
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    ISSN: 1432-0878
    Keywords: Key words: Development ; Mucosal surface area ; Ultrastructure ; Villus ; Microvillus ; Morphometric analysis ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The mucosal surface area of the chicken duodenum, jejunum, and ileum was determined during development (from 1-day to 12-week-old animals). The morphometric analysis was performed at three magnification levels. The nominal (serosal) surface area was determined at the macroscopic level, from intestinal length and perimeter. Villus and microvillus amplification factors were estimated at light-microscopic and transmission electron-microscopic levels, respectively. The results show, during the period considered: (1) a similar increase in nominal surface area for the three segments (6.5 to 7.2-fold), (2) a rise followed by a slight decrease in the villus amplification factor in the third week of age in the duodenum, a two-fold increase of this variable in the jejunum and no significant developmental variations in the ileum, (3) an increase in the microvillus amplification factor of 1.5-fold in the duodenum and jejunum and of 1.2-fold in the ileum, although a pronounced decrease in the first week of age was observed in the three segments. In conclusion, total mucosal surface area increased, from 1 day to 12 week, 12- to 13-fold in the duodenum and ileum and 20-fold in the jejunum.
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    URL: http://dx.doi.org/10.1007/s004410050909
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    Ultrastructural localization of the iodination centre in the endostyle of the adult amphioxus (Branchiostoma lanceolatum) (1985)
    Springer
    Cell & tissue research 241 (1985), S. 267-273 
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    ISSN: 1432-0878
    Keywords: Endostyle ; Autoradiography ; Ultrastructure ; Iodination ; Amphioxus, adult (Branchiostoma lanceolatum)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The site of iodination in the endostyle of the adult amphioxus was examined by light-and electron-microscopic autoradiography. In accordance with previous studies, light-microscopic autoradiography showed a distinct accumulation of autoradiographic grains at the apical end of epithelial cells in the lateral part of the endostyle. In the electron microscope two distinct cellular zones were identified in an approximate position of the light-microscopic zone 5. Zone 5a, not previously recognized, was adjacent to zone 4 and consisted of six to nine rows of cells free of characteristic granules. Cells in zone 5b contained large “mucous” granules and had, in previous ultrastructural studies, been identified as belonging to the typical zone 5. Four or less incomplete rows of granule-containing cells, not observed in previous studies, marked the border between zones 5b and 6. After incubation in 125I for 5 min, electron-microscopic autoradiography showed a selective concentration of label to zone 5a, which, thus, corresponds to the iodination centre seen in the light microscope. The grains were associated with cilia and microvilli in the lumen. After longer incubation times (30, 60, 90 min) grains were still concentrated at the surface of zone 5a but were also associated with the surface of zones 5b and 6. Grains were also located over the cytoplasm of all three zones. They were associated with vesicles and lysosome-like structures, suggesting secondary uptake of labelled products by endocytosis. Methimazole, an inhibitor of peroxidase, abolished the autoradiographic reaction. In conclusion, the site of iodination in the endostyle of amphioxus is located in zone 5a, which has not previously been ultrastructurally defined. Iodination in the endostyle is an extracellular process, but secondary uptake by endocytosis appears to occur.
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    Electron-microscopic observations of the gravity receptor epithelia of normal and spinner juvenile Octopus maya (1985)
    Springer
    Cell & tissue research 240 (1985), S. 701-704 
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    ISSN: 1432-0878
    Keywords: Maculae ; Cephalopods ; Statolith defects ; Ultrastructure ; Spinner octopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron microscopy of the gravity receptor epithelia (maculae) of statocysts of normal and “spinner” juvenile Octopus maya showed differences between the structures of the hair cells, supporting cells, and afferent neurons of these cephalopods. The maculae of spinner animals were approximately 30% smaller in their surface area and had 40% fewer hair cells. Moreover, the average distance between randomly-chosen hair bundles in scanning electron micrographs of maculae of normal animals was significantly greater (4.33±6.47 μm) than those of maculae of spinner animals (3.38±4.90 μm; P〈0.0001). The sectional area of the supporting cell's microvilli in spinners maculae was larger (0.16±0.18 μm) than those of normal (0.10±0.10 μm; P〈0.0001) O. maya. The morphological differences observed between certain structural components of the maculae of normal and spinner O. maya may be related to the absence and/or malformation of the neuroepithelial suprastructures in spinners. This may have direct or indirect effects related to their inability to orient to gravity with these organs.
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    Fibronectin and its relation to the basal lamina and to the cell surface in the chicken blastoderm (1985)
    Springer
    Cell & tissue research 241 (1985), S. 391-397 
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    ISSN: 1432-0878
    Keywords: Fibronectin ; Gastrulation ; Immunocytochemistry ; Ultrastructure ; Basal lamina ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural distribution of fibronectin immunoreactivity was investigated in the chicken embryo during late gastrulation. Sites of binding of anti-fibronectin antibodies were ascribed to the basal lamina and associated structures, and to the cell surface. The fibronectin-rich basal lamina was resolved into (1) a lamina densa, which appears as a continuous, dense sheet, (2) a lamina lucida, consisting of anchoring cords between lamina densa and epithelial cells, and (3) a lamina intima, closely juxtaposed to the cell surface. Cell-surface labelling was also observed in mesoblast cells, and along the dorsal side of the deep-layer cells. The ventral side of the latter cells was poorly stained in the endophyllic crescent, except in coated pits, and more regularly stained at the level of definitive endoblast. Some structures associated with the basal lamina reacted intensely with anti-fibronectin antibodies. These are (1) the interstitial bodies, which are aggregates of extracellular material, and (2) a kind of fibril or tubule, embedded in a fibronectin matrix and mainly found in the endophyllic crescent. Some intracellular labelling was found in most deep-layer cells, in few epiblast cells, never in mesoblast cells. These results extend previous studies on the localization of fibronectin, and correlate its presence and surface topology with its postulated role in migration of mesoblast cells on the basal lamina which, chemically, constitutes an appropriate substrate.
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    The fine structure of the tarsal glands of the honeybee Apis mellifera L. (Hymenoptera) (1985)
    Springer
    Cell & tissue research 240 (1985), S. 153-158 
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    ISSN: 1432-0878
    Keywords: Tarsal glands ; Ultrastructure ; Apis mellifera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tarsal glands are located in the 6th tarsomere of adult honeybee queens, workers and drones. Their structural features are not cast or sex specific. The glandular epithelium is lined by a thin endocuticular layer. A cuticular pocket is formed from a postimaginal delamination of the cuticle secreted by the glandular epithelium. The apical plasma membrane of the glandular cells shows numerous cristae and microvilli lining large crypts that communicate with the subcuticular space. Pinocytotic vesicles, multivesicular bodies and residual dense bodies are present in the apical part of the glandular cells. The RER is well developed in perinuclear and basal parts of the glandular cells, but the Golgi apparatus is a discrete organelle without secretory granules. No exocytotic secretory structures were observed. To reach the glandular pocket, the non-proteinaceous secretory product must pass across the subcuticular space, the cuticular intima, the space between the intima and the cuticular wall, and the cuticular wall of the glandular pocket.
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    Effects of temperature and bright light on myeloid bodies in the retinal pigment epithelium of the newt, Notophthalmus viridescens (1985)
    Springer
    Cell & tissue research 241 (1985), S. 623-628 
    Details
    ISSN: 1432-0878
    Keywords: Retinal pigment epithelium ; Myeloid bodies ; Morphometry ; Ultrastructure ; Endoplasmic reticulum ; Lighting effects ; Temperature effects ; Urodeles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Myeloid bodies (MBs) are specialized regions of endoplasmic reticulum which occur in the retinal pigment epithelium of a number of vertebrate species. In the newt, Notophthalmus viridescens, the effects of temperature and brief exposure to bright flashed-light on myeloid bodies have been studied. Morphometric analysis has shown that in animals sampled at 06.30 h, myeloid body sectional area remained unchanged in animals maintained in the cold (1°C), compared with control animals at 15°C, whereas phagosome area was significantly increased. At higher temperatures (30° C), myeloid body area was observed to decline from control values, while phagosome area was substantially increased. During the first 2 h of the light phase of a normal (15° C) 12:12 LD lighting cycle, myeloid-body sectional area dropped significantly from values recorded in the latter part of the dark phase. This reduction of MB area at the normal time of “lights-on” was greatly reduced when animals experienced an extended period of darkness. When animals experiencd a bright flashed-light at the normal time of “lights-on”, followed by a period of extended darkness, reduction in MB area was less pronounced when compared to cycled control animals. These results are discussed in the context of the hypothesis (Yorke and Dickson 1984) that MBs represent a temporary storage site for lipids entering the pigment epithelium after phagocytosis of shed outer segment tips, prior to their permanent storage in lipid droplets. These results are consistent with the proposal that myeloid bodies are removed from the cytoplasm of the newt pigment epithelium by metabolic processes which are active over time, but accelerated by increased temperatures or the presence of light.
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    Implementation of periodic acid-thiosemicarbazide-silver proteinate staining for ultrastructural assessment of muscle glycogen utilization during exercise (1985)
    Springer
    Cell & tissue research 242 (1985), S. 229-232 
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    ISSN: 1432-0878
    Keywords: Skeletal muscles ; Ultrastructure ; Exercise ; Glycogen ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these “depleted” type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.
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    Apical tubular network in the rat kidney proximal tubule cells studied by thick-section and scanning electron microscopy (1997)
    Springer
    Cell & tissue research 288 (1997), S. 317-325 
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    ISSN: 1432-0878
    Keywords: Key words: Kidney (proximal tubule) ; Apical tubule ; Endosome ; Ultrastructure ; Endocytosis ; Membrane recycling ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The apical cytoplasm of several absorbing epithelia contains well-developed apical tubules (AT) which contribute to membrane recycling from endocytic vacuoles to the apical cell membrane. In this study, we examined three-dimensional structures of the AT in rat kidney proximal tubule cells by transmission and scanning electron microscopy. In thin sections, the AT appeared as straight tubules with a rather constant diameter (70–90 nm), but others were curved and, occasionally, branching. No AT were labeled with the marker for the external cell surface (ruthenium red) or exhibited histochemical enzyme activity for lysosomal hydrolase (acid phosphatase). After intravenous injection of horseradish peroxidase, it was absorbed in the kidney proximal tubule cells and the AT were labeled with HRP reaction products. Stereo-viewing of the labeled AT in thick sections revealed that they formed an interconnected tubular network. Scanning electron microscopy allowed a three-dimensional view of the AT, in which a network of branching and anastomosing tubules was revealed. These observations indicate that the AT are intracellular endosomal compartments which form an extensive tubular network in the apical cytoplasm. The possibility that this apical tubular network serves as a large membrane store for membrane recycling is discussed.
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    Cytochemical and X-ray microanalysis studies of intracellular calcium pools in scale-bearing cells of the coccolithophoridEmiliania huxleyi (1985)
    Springer
    Protoplasma 124 (1985), S. 1-9 
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    ISSN: 1615-6102
    Keywords: Calcium localization ; Coccolithophorids ; Emiliania huxleyi ; Pyroantimonate ; Ultrastructure ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Emiliania huxleyi is a coccolithophorid with a life cycle including a stage characterized by the occurrence of a scale-bearing cell type. The scales are composed of organic material and are produced in the cisternae of the Golgi apparatus. The present report deals with the ultrastructural calcium localization in scale-bearing cells using cation-precipitating agents. Cations were precipitated either with potassium pyroantimonate alone or according to a combined procedure in which cells are treated first with potassium oxalate, or potassium carbonate, or potassium phosphate, and then with potassium pyroantimonate. The distribution of electron-opaque deposits was the same when visualized by all four techniques. The most extensive deposits occurred in the Golgi apparatus, the “peripheral space” (a cellular compartment totally encompassing the protoplast), the multivesicular bodies, and the cell vacuole. X-ray microanalysis revealed that calcium was a constituent of the electron-opaque deposits. The uptake and transport of calcium, as universal functions of the Golgi apparatus, are discussed.
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    Preprophasic establishment of division polarity in monoplastidic mitosis of hornworts (1985)
    Springer
    Protoplasma 124 (1985), S. 175-183 
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    ISSN: 1615-6102
    Keywords: Division polarity ; Hornworts ; Microtubules ; Mitosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Preprophase in the monoplastidic mitotic cells ofPhaeoceros andNotothylas is characterized by the establishment of a division site in the absence of a typical preprophase band. The future cytokinetic plane is predicted by plastid orientation and development of an elaborate preprophasic microtubule system perpendicular to the division plane. Division of the single plastid is initiated early in preprophase and the constricting plastid migrates to a position perpendicular to the future plane of division. Plastid orientation assures that division of the plastid by mid-constriction will result in distribution of a plastid to each daughter cell. Microtubules parallel the long axis of the plastid and are most numerous adjacent to the nucleus which becomes elongated in the future spindle axis. We conclude that the division site is a fundamental component of the cytokinetic apparatus involved in the determination of cleavage plane prior to nuclear division.
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    Ultrastructure of freeze-substitutedFrankia strain HFPCcI 3, the actinomycete isolated from root nodules ofCasuarina cunninghamiana (1985)
    Springer
    Protoplasma 127 (1985), S. 64-72 
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    ISSN: 1615-6102
    Keywords: Actinomycete ; Casuarina ; Frankia ; Freeze-substitution ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frankia strain HFPCcI 3 is an actinomycete isolated from root nodules ofCasuarina cunninghamiana. In culture it exhibits typicalFrankia morphology and may produce three distinct morphological forms: branching septate hyphae, terminal or intercalary sporangia, and specialized structures termed vesicles which are the purported site of nitrogenase activity. An examination of the ultrastructure of all three morphological forms using both conventional chemical fixation (CF) and quick-freezing followed by freeze-substitution (FS) reveals some interesting differences between the two fixation methods. Unique to FS material are: 1. smooth membrane profiles; 2. lack of mesosomes; 3. lack of discernible nucleoid regions with condensed chromatin; 4. clarity of cytoplasmic elements such as ribosomes and granular bodies; 5. large cytoplasmic tubules in hyphae and young sporangia; 6. outer wall layer not widely separated from the spherical portion of the vesicle, and 7. bundles of microfilaments in vesicles. The quality of preservation after FS appears to be far superior to that obtained with CF. Accordingly the structures observed after FS are thought to represent more faithfully the structure of the living cell.
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    Ultrastructure of endopolyploid antipodals inAconitum vulparia Rchb. (1985)
    Springer
    Protoplasma 127 (1985), S. 163-170 
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    ISSN: 1615-6102
    Keywords: Aconitum vulparia ; Antipodals ; Endopolyploid cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the antipodals ofAconitum vulparia Rchb. was studied in mature embryo sacs. Antipodal cell wall thickness varies in different parts of the cells. The antipodals resemble transfer cells with distinctly marked wall ingrowths which are particularly well developed in the chalazal part and between the antipodals. A few plasmodesmata occur in the cell wall between the antipodals and the central cell. The cytoplasm is rich in ribosomes which occur free or bound to the membranes of the well developed endoplasmic reticulum. Only in the micropylar region of the cells are some larger vacuoles found. The antipodals contain numerous mitochondria, plastids and apparently active dictyosomes. Vesicles with electron dense contents, microbodies, multivesicular bodies as well as lipid droplets and small multiple concentric cisternae are also present in the cytoplasm. The giant endopolyploid nuclei have lobed outlines, especially at the chalazal side of the nuclei. Ultrastructural features, especially the occurrence of numerous free ribosomes and the development of extensive rough endoplasmic reticulum, suggest high metabolic activity in the growing and differentiating antipodals of this species.
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    Ultrastructural aspects of cytoplasmic male sterility inPetunia hybrida (1985)
    Springer
    Protoplasma 127 (1985), S. 230-240 
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    ISSN: 1615-6102
    Keywords: Cytoplasmic male sterility ; Mitochondria ; Petunia hybrida ; Tapetum ; Ultrastructure ; Vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Anther development of isogenic male fertile and cytoplasmic male sterile types ofPetunia hybrida cv. Blue Bedder is studied by electron microscopy. First deviation in sporogenesis of the sterile type, is observed during leptotene stage of the meiocytes. Initial aberration is represented by the presence of large vacuoles in the cytoplasm of the tapetal cells. These vacuoles reveal the first aspects of degeneration; no other ultrastructural differences are observed. Vacuolation is accompanied by the condensation of cytoplasmic organelles. The tapetal cells become distorted and ultrastructural aberrations in mitochondria do occur. The mitochondria elongate and contain several tubular cristae. Substantial evidence suggests, that cytoplasmic male sterility in petunia is encoded by the mitochondrial genome (Boeshore el al. 1983). However, before degeneration becomes manifest, no consistent ultrastructural differences in mitochondrial organization are observed. Abortion of the tapetum and the sporogenous tissue in cytoplasmic male sterile plants, generally follows a corresponding pattern. Ultimately, the cells are highly distorted, the nucleus is disrupted and the cytoplasm disorganized. Mitochondria and plastids degenerate and many lipid droplets are present.
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    Structure and function in the grass ligule: The membranous ligule ofLolium temulentum L. as a secretory organ (1985)
    Springer
    Protoplasma 127 (1985), S. 128-132 
    Details
    ISSN: 1615-6102
    Keywords: Ligule ; Lolium temulentum L. ; Poaceae ; Polysaccharide cytochemistry ; Secretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using phosphotungstic acid and periodic acid/thiocarbohydrazide/silver proteinate (Thiéry test) aspects of polysaccharide ultracytochemistry were studied in the membranous ligule ofLolium temulentum L. Staining results are presented for all three tissues-abaxial and adaxial epidermes and mesophyll-but discussed only for the epidermes. PTA- and PATAg-staining of the adaxial epidermis suggested synthesis of a conjugated polysaccharide material in this tissue, its accumulation in the periplasmic space and its subsequent secretion to the outside of the ligule via gaps in the cuticle. The ligule of this grass is considered to be a secretory organ.
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    URL: http://dx.doi.org/10.1007/BF01273709
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    An efficient procedure for isolation of nuclei from plant protoplasts (1985)
    Springer
    Protoplasma 128 (1985), S. 184-189 
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    ISSN: 1615-6102
    Keywords: Nuclear isolation ; pH ; Protoplasts ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The present communication describes an easy, efficient and rapid method for isolation of nuclei from plant protoplasts. Release of nuclei is accomplished by disruption of protoplasts in an appropriate buffer containing a very low concentration (0.01%) of the detergent Triton X-100. The pH of the nuclei isolation buffer (5.3) played a critical role in the recovery of stable nuclei in large numbers. Supplementation of buffer (10 mM MES) with spermine (0.1 mM), dithiothreitol (2.5 mM), ethylenediaminetetraacetic acid (2.5 mM) and Nad and KCl (10 mM each) improved nuclear yield and quality. With the method developed it is possible to routinely recover 95% nuclei from the protoplasts within 30 minutes. The nuclear preparations are of high purity with little detectable cytoplasmic contamination and no clumping of the nuclei. The structural integrity of the nuclei has been assessed and confirmed by Nomarski differential interference contrast optics and ultrastructural observations.
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    URL: http://dx.doi.org/10.1007/BF01276340
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    An ultrastructural approach to the adaptive role of the cell wall in the intertidal algaFucus virsoides (1985)
    Springer
    Protoplasma 128 (1985), S. 208-217 
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    ISSN: 1615-6102
    Keywords: Cation exchange ; Cell wall ; Fucus virsoides ; Intertidal seaweeds ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the cell wall and the distribution of alginate, cellulose and fucoidans were studied in the intertidal algaFucus virsoides. Microanalysis and precipitation with KPA revealed a cation localization in the wall, mainly corresponding with sulphated polysaccharide distribution. Thus, the adaptive resistance to changes in ionic environment seems to take place through a cation binding to the cell wall polysaccharides, principally at the thallus surface, employing an avoidance mechanism.
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    URL: http://dx.doi.org/10.1007/BF01276343
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    Ultrastructural characterisation of cells specialised for nitrogen fixation in a non-heterocystous cyanobacterium,Trichodesmium spp. (1997)
    Springer
    Protoplasma 197 (1997), S. 76-85 
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    ISSN: 1615-6102
    Keywords: Cell differentiation ; Immunolocalisation ; Nitrogenase ; Non-heterocystous cyanobacteria ; Trichodesmium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Trichodesmium is the first described example of a filamentous cyanobacterium without heterocysts that contains cells specialised for nitrogen fixation. The ultrastructure of cells with and without nitrogenase were compared using primarilyTrichodesmium tenue Wille, but alsoT. thiebautii Gomont andT. erythraeum Ehrenberg et Gomont. Immunohistochemistry demonstrated that the cytoplasm of certain cells was densely labelled with antibodies against Fe-protein (dinitrogenase reductase). Comparative TEM-image analysis revealed that these cells were also distinguished by a denser thylakoid network, dividing the vacuole-like space into smaller units. The nitrogenase-containing cells also exhibited less extensive gas vacuoles as well as fewer and smaller cyanophycin granules compared to cells which lacked nitrogenase. Carboxysomes were present in both cell types in equal proportion. Longitudinal sections showed that cells with nitrogenase were arranged adjacent to each other, and that groups of cells with and without nitrogenase may coexist in the same trichome. The correlation between modifications in ultrastructure and the presence of nitrogenase suggests a new type of cyanobacterial cell specialisation related to nitrogen fixation. The results obtained also question the systematic affiliation of the genusTrichodesmium.
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    URL: http://dx.doi.org/10.1007/BF01279886
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    Relationships between structure and motility ofAlbizzia motor organs: Changes in ultrastructure of cortical cells during dark-induced closure (1985)
    Springer
    Protoplasma 128 (1985), S. 72-79 
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    ISSN: 1615-6102
    Keywords: Albizzia ; Cytoskeleton ; Membranes ; Motility ; Pulvinus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Paired leaflets ofAlbizzia julibrissin spread apart (open) in the daytime and fold together (close) at night. We examined the structure of cells in open and closedAlbizzia motor organs (pulvini) to identify reversible changes in structure associated with motility. Pulvini were fixed in glutaraldehyde and stained using conventional methods. The pulvinus has a central vascular cylinder bordered by thick-walled collenchyma cells, in turn surrounded by an endodermis and many layers of cortical parenchyma. Cortical cells in the extensor undergo large changes in shape during leaflet closure linked with: formation of wall infoldings, development of a large periplasmic space filled with fibrils and membranes, development of lobes on the nucleus, evagination of the nuclear outer envelope membrane, break-up of the large central vacuole to form many small vacuoles, and linking of the plasmalemma to inner regions of the cytoplasm by microfilaments. Cortical cells in the flexor, by contrast, remain relatively stable during leaflet movement. Microtubules are present near the plasmalemma in both extensor and flexor cells; in the extensor, spherical coated vesicles are located near the microtubules. The possible function of these structures in regulating intracellular shuttling processes is discussed.
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    URL: http://dx.doi.org/10.1007/BF01273238
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    Myoendothelial junctions in blood vessels of a teleost (Prochilodus scrofa) pancreas and caeca (1985)
    Springer
    Protoplasma 128 (1985), S. 224-226 
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    ISSN: 1615-6102
    Keywords: Blood vessels ; Myoendothelial junctions ; Teleosts ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Close contacts between endothelial and smooth muscle cells in teleost (Prochilodus scrofa) blood vessels are described for the first time in the present study. More frequently are seen finger-like, club-shaped or foot-like endothelial processes that come into close contact with the plasma membrane of a smooth muscle cell. Rarely, some myoendothelial contacts occur between the finger-like protrusions that arise from both the endothelial and from the smooth muscle cells. The functional significance of the myoendothelial connection is discussed.
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    URL: http://dx.doi.org/10.1007/BF01276345
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    Ultrastructure of the flagellar apparatus inPleurochrysis (classPrymnesiophyceae) (1985)
    Springer
    Protoplasma 125 (1985), S. 24-35 
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    ISSN: 1615-6102
    Keywords: Coccolithophorid ; Flagellar apparatus:Pleurochrysis ; Prymnesiophyceae ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the flagellar apparatus of aPleurochrysis, a coccolithophorid was studied in detail. Three major fibrous connecting bands and several accessory fibrous bands link the basal bodies, haptonema and microtubular flagellar roots. The asymmetrical flagellar root system is composed of three different microtubular roots (referred to here as roots 1,2, and 3) and a fibrous root. Root 1, associated with one of the basal bodies, is of the compound type, constructed of two sets of microtubules,viz. a broad sheet consisting of up to twenty closely aligned microtubules, and a secondary bundle made up of 100–200 microtubules which arises at right angles to the former. A thin electron-dense plate occurs on the surface of the microtubular sheet opposite the secondary bundle. The fibrous root arises from the same basal body and passes along the plasmalemma together with the microtubular sheet of root 1. Root 2 is also of the compound type and arises from one of the major connecting bands (called a distal band) as a four-stranded microtubular root and extends in the opposite direction to the haptonema. From this stranded root a secondary bundle of microtubules arises at approximately right angle. Root 3 is a more simple type, composed of at least six microtubules which are associated with the basal body. The flagellar transition region was found to be unusual for the classPrymnesiophyceae. The phylogenetic significance of the flagellar apparatus in thePrymnesiophyceae is discussed.
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    Ultrastructural localization of basic proteins ofBlastocystis hominis (1997)
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    Protoplasma 200 (1997), S. 31-34 
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    ISSN: 1615-6102
    Keywords: Blastocystis hominis ; Central vacuole ; Accumulation ; Basic proteins ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Basic proteins ofBlastocystis hominis were detected by the ammoniacal silver and ethanolic phosphotungstic acid techniques using electron microscopy. The central vacuole showed many silver grains when treated with ammoniacal silver and an increased electron density when treated with phosphotungstic acid. The intensity of positive reactions correlated with the electron density of the central vacuole, because cells having an electron-lucent central vacuole showed no silver grain deposits. Since it is known that the concentration of electron-dense materials in the central vacuole increases during log phase of growth, and then decreases in stationary phase, this organelle must accumulate basic proteins during cell growth.
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    URL: http://dx.doi.org/10.1007/BF01280732
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    The influence of lignification on the development of vascular tissue inVigna radiata L. (1985)
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    Protoplasma 124 (1985), S. 87-95 
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    ISSN: 1615-6102
    Keywords: L-α-aminooxy-β-phenylpropionic acid ; Lignification ; Secondary cell wall ; Ultrastructure ; Vigna radiata ; Xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the early development of mungbean seedlings, treatment with L-α-aminooxy-β-phenylpropionic acid (AOPP), a potent specific inhibitor of phenylalanine ammonia-lyase, results in an inhibition of anthocyanin and lignin synthesis. The xylem vessels of the hypocotyl and root of AOPP treated seedlings collapse, and the cellulose microfibrils of the unlignified secondary wall are separated from one another and lie disorganized in the lumen of the mature xylem cell. The differentiation of the secondary cell wall appears unaffected by AOPP treatment, as does the ultrastructure of the wall of the mature phloem fibers of the root which is also lignified in untreated tissue. The results are discussed in the light of current thinking on the role and development of lignification in the xylem vessel.
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    Ultrastructural studies on plastids of generative and vegetative cells inLiliaceae 3. Plastid distribution during the pollen development inGasteria verrucosa (Mill.) Duval (1985)
    Springer
    Protoplasma 124 (1985), S. 123-129 
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    ISSN: 1615-6102
    Keywords: First pollen mitosis ; Gasteria verrucosa ; Male plastid inheritance ; Pollen development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper describes the development of pollen grains ofGasteria verrucosa from the late microspore to the mature two-cellular pollen grain. Ultrastructural changes and the distribution of plastids as a result of the first pollen mitosis have been investigated using light and electron microscopy. The microspores as well as the generative and the vegetative cell contain mitochondria and other cytoplasmic organelles during all of the observed developmental stages. In contrast, the generative cell and the vegetative cell show a different plastid content. Plastids are randomly distributed within the microspores before pollen mitosis. During the prophase of the first pollen mitosis the plastids become clustered at the proximal pole of the microspore. The dividing nucleus of the microspore is located at the distal pole of the microspore. Therefore, the plastids are not equally distributed into both the generative and the vegetative cell. The possible reasons for the polarization of plastids within the microspore are briefly discussed. The lack of plastids in the generative cell causes a maternal inheritance of plastids inGasteria verrucosa.
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    URL: http://dx.doi.org/10.1007/BF01279731
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    Mitosis in the basidiomycete fungusTulasnella araneosa (1985)
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    Protoplasma 126 (1985), S. 1-18 
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    ISSN: 1615-6102
    Keywords: Mitosis ; Ultrastructure ; Phylogeny ; Basidiomycotina ; Tulasnella araneosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This is a report of a light and electron microscopic study of mitosis in the basidiomycetous fungusTulasnella araneosa. The study employs serial section analyses of nuclei preselected with fluorescence microscopy. It is the first such study of nuclear division in theTulasnellaceae and the first of conjugately dividing nuclei in basidiomycetous hyphal segments lacking clamp connections. Mitosis inT. araneosa is unusual in that the spindle pole body (SPB) develops asymmetrically; the SPB middle piece is large and transversely curved; and the nuclear envelopes of adjacent late anaphase nuclei fuse. Analyses of mitotic characteristics used for phylogenetic purposes indicate that, of the many characters available, only SPB characteristics are presently valuable. Available evidence indicates that the SPB ofT. araneosa is more different from that ofUredinales than it is from representatives of the other four orders ofBasidiomycotina that have been thoroughly studied.
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    URL: http://dx.doi.org/10.1007/BF01287668
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    Massive ribonucleoprotein bodies in gametophyte vegetative cells of the mossTimmiella barbuloides (Brid.) Moenk (1985)
    Springer
    Protoplasma 127 (1985), S. 204-211 
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    ISSN: 1615-6102
    Keywords: Biogenesis ; Cytochemistry ; Ribonucleoprotein bodies ; Ribosomes ; Timmiella barbuloides (Musci) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Vegetative cells of the gametophyte phase of the mossTimmiella barbuloides (Pottiales) are characterized by large cytoplasmic bodies of spherical shape (SBs) whose ribonucleoprotein composition is cytochemically demonstrated. SBs seem to be derived from massive aggregation of cytoplasmic ribosomes, with possible participation by rough endoplasmic reticulum elements. SBs have been found in stereids, parenchymatous cells and young hydroids of the gametophyte stem, and in euricysts of the leaf nerve. The SBs develop early in the course of cell differentiation and, once formed, persist until advanced stages of cell senescence.
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    URL: http://dx.doi.org/10.1007/BF01276264
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    The ultrastructure of the plasmodesmata of the salt glands ofTamarix as revealed by transmission and freeze-fracture electron microscopy (1985)
    Springer
    Protoplasma 125 (1985), S. 13-23 
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    ISSN: 1615-6102
    Keywords: Plasmodesmata ; Ultrastructure ; Freeze-fracture ; Salt glands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Numerous plasmodesmata occur in the walls between the secretory cells ofTamarix salt glands. The plasmalemma bounds the plasmodesmata and is continuous from cell to cell. In freeze-fracture, the e-face of the plasmalemma within the plasmodesmata is virtually devoid of intramembranous particles while, in contrast, the p-face is decidedly enriched with particles. The axial components appear to be a tightly curved membrane bilayer, as judged from measurements and their appearance in freeze-fracture, and the e-face of this membrane is also devoid of particles. Observations from both thin sections and freeze-fracture replicas indicate the presence of a circular cluster of six particles around the axial component near the cytoplasmic termini of the plasmodesmata. These particles extend from the p-face of the axial component to the p-face of the plasmalemma. These observations are summarized in a model.
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    Structure and histochemistry of the extrafloral nectary ofAcacia terminalis (Salisb.) MacBride (Leguminosae, Mimosoideae) (1985)
    Springer
    Protoplasma 127 (1985), S. 21-30 
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    ISSN: 1615-6102
    Keywords: Acacia terminalis ; Extrafloral nectary ; Histochemistry ; Secretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The extrafloral nectary ofAcacia terminalis is of the flat type and is located on the adaxial surface of the petiole of the bipinnate leaf. The secretory area is restricted to the base of the trough and no gaps or pores were detected by staining with vital dyes. Between the vascular bundles beneath the nectary and the surface cuticle there were three cell types. The cells of the flanking zone adjacent to the vascular bundles did not appear to be producing secretion whereas the cells of the glandular and secretory zones were secreting. The cells of the glandular zone were elongated whereas those of the surface secretory zone were spherical. Both had endoplasmic reticulum and Golgi bodies with secretory vesicles which were observed in close association with the plasmalemma. Secretion accumulated in the intercellular spaces of the glandular zone cells and forced the cells of the secretory zone apart. Symplastic contact was maintained in all cell types by plasmodesmata which were often associated with endoplasmic reticulum. Secretion accumulated beneath the cuticle which was distended but remained intact on the surface of the secretion.
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    URL: http://dx.doi.org/10.1007/BF01273698
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    Ultrastructural ontogeny of leaf cavity trichomes inAzolla implies a functional role in metabolite exchange (1985)
    Springer
    Protoplasma 129 (1985), S. 10-27 
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    ISSN: 1615-6102
    Keywords: Azolla ; Anabaena ; Symbiosis ; Nitrogen fixation ; Trichome ; Transfer cell ; Ontogeny ; Ultrastructure ; Gland ; Metabolite exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Anabaena azollae is associated with two types of multicellular epidermal trichomes inAzolla leaf cavities, the simple and branched hairs. The observation of transfer cell ultrastructure in some hair cells led to speculation that the cavity hairs might participate in metabolite exchange between the symbionts. The developmental ontogeny of cavity trichomes is described here, using transmission electron microscopy, with a goal of improving our understanding of possible functions of these structures in the symbiosis. The observations have established that all cells of simple and branched hairs develop the structural characteristics of transfer cells, but not simultaneously. Rather, there is an acropetal succession of transfer cell ultrastructure beginning in terminal cells, moving to body cells where present, and ending in stalk cells. The transfer cell stage is followed immediately by senescence in all hair cells. The timing of transfer cell differentiation, considered together with information from other studies, suggests that branched hairs may be involved in exchange of fixed nitrogen between the symbionts, while simple hairs may participate in exchange of fixed carbon fromAzolla toAnabaena.
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    The initiation, development and structure of root nodules inElaeagnus angustifolia L. (Elaeagnaceae) (1985)
    Springer
    Protoplasma 128 (1985), S. 107-119 
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    ISSN: 1615-6102
    Keywords: Actinorhizal root nodules ; Development ; N2 fixation ; Elaeagnus ; Frankia ; Symbiosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A correlated light and electron microscopic study was undertaken of the initiation and development of root nodules of the actinorhizal tree species,Elaeagnus angustifolia L. (Elaeagnaceae). Two pure culturedFrankia strains were used for inoculation of plants in either standing water culture or axenic tube cultures. Unlike the well known root hair infection of other actinorhizal genera such asAlnus orMyrica the mode of infection ofElaeagnus in all cases was by direct intercellular penetration of the epidermis and apoplastic colonization of the root cortex. Root hairs were not involved in this process and were not observed to be deformed or curled in the presence of the actinomyceteFrankia. In response to the invasion of the root, host cells secreted a darkly staining material into the intercellular spaces. The colonizingFrankia grew through this material probably by enzymatic digestion as suggested by clear dissolution zones around the hyphal strands. A nodule primordium was initiated from the root pericycle, well in advance of the colonizingFrankia. No random division of root cortical cells, indicative of prenodule formation was observed inElaeagnus. As the nodule primordium grew in size it was surrounded by tanninised cells of a protoperiderm. The endophyte easily traversed this protoperiderm, and once inside the nodule primordium cortex ramified within the intercellular spaces at multiple cell junctions. Invasion of the nodule cortical cells occurred when a hyphal branch of the endophyte was initiated and grew through the plant cell wall, again by apparent enzymatic digestion. The plant cell plasmalemma of invaded cells always remained intact and numerous secretory vesicles fused with it to encapsulate the advancingFrankia within a fibrous cell wall-like material. Once within the host cell some endophyte cells began to differentiate into characteristic vesicles which are the presumed site of nitrogen fixation. This study clearly demonstrates that alternative developmental pathways exist for the development of actinorhizal nitrogen-fixing root symbioses.
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    Formation of the plasma membrane during regeneration ofParamecium caudatum (1985)
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    Protoplasma 125 (1985), S. 94-102 
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    ISSN: 1615-6102
    Keywords: Biogenesis ; Plasma membrane ; Regeneration ; Ultrastructure ; Paramecium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fragments ofParamecium caudatum cells obtained by merotomy were fixed in 1% OsO4 within 5 seconds after cutting. The ultrastructure of the damaged area of the fragment was studied in oriented ultrathin sections and by scanning electron microscopy. The cytoplasm exposed by merotomy was covered during a few seconds with a new membrane. This was a typical trilaminar membrane continuous with the plasma membrane covering the undamaged surface of the cell. The surface over the wound was wrinkled into irregular grooves and ridges. The cytoplasm, mitochondria and trichocysts in the injured region were electron translucent. The cytoplasm under the new membrane contained an unusually high amount of small membrane vesicles, 20–90 nm in diameter. These were probably the remnants of subpellicular alveoli and the plasma membrane destroyed by microsectioning. The possibility that the exposed cytoplasm would be covered by mere shifting of the existing plasma membrane can be excluded. The complex structure of the cortex with its subpellicular alveoli and regularly distributed cilia provide a strong argument against this notion. It seems probable that the new membrane was built up from the available molecular material,e.g., phospholipids and proteins present in the cytoplasm. Fragments of the membrane and alveolar membranes in the form of small vesicles may have also been included into the new membrane.
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    The ultrastructure of mitosis inIsochrysis galbana parke (Prymnesiophyceae) (1985)
    Springer
    Protoplasma 125 (1985), S. 140-151 
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    ISSN: 1615-6102
    Keywords: Mitosis ; Cytokinesis ; Alga ; Isochrysis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis and cytokinesis have been studied in the flagellate algaIsochrysis galbana Parke (Prymnesiophyceae). Nuclear division is preceded by replication of the flagella and haptonema, the Golgi body and the chloroplast; fission in the chloroplast occurs in the region of the pyrenoid. During prophase, spindle microtubules radiating from two ill-defined poles are formed. The nuclear envelope breaks down and the chromatin condenses. At metaphase the spindle is fully developed, some pole-to-pole microtubules passing through the well-defined chromatin plate, others terminating at it. No kinetochores or individual chromosomes were observed. By late metaphase, many Golgi-derived vesicles may be seen against the two poleward faces of the metaphase plate. During anaphase, the two daughter masses of chromatin move towards the poles. In early telophase, the nuclear envelope of each daughter nucleus is complete only on the side towards the adjacent chloroplast, remaining open on the interzonal side. However, during telophase each nucleus becomes reorientated so that it lies lateral to the long axis of the spindle and with its open side towards the chloroplasts. By late telophase, each new nuclear envelope is complete and confluence with the adjacent chloroplast ER established. Cytokinesis and subsequent segregation of the daughter cells are effected by the dilation of Golgi- and ER-derived vesicles in the interzonal region. No microtubular structures are involved. Comparisons with the results from other studies of mitosis in members of thePrymnesiophyceae show that they all have a number of features in common, but that there are differences in detail between species.
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    Physiological and structural changes in the chloroplast of the green alga Micrasterias denticulata induced by UV-B simulation (1997)
    Springer
    Plant ecology 128 (1997), S. 55-64 
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    ISSN: 1573-5052
    Keywords: Algae ; Chloroplast ; Micrasterias ; Photosynthesis ; Ultrastructure ; UV-B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of postmitotic growing and non-growing cells of the unicellular green alga Micrasterias denticulata to different UV-B cut-off wavelengths together with simulated sunlight in a sun simulator has revealed a marked resistence of the algae against strong irradiation. While down to a cut-off wavelength of 284 nm irradiated during the most sensitive stage of cell development chloroplast ultrastructure remains unaffected, severe changes in arrangement and structure of stroma and grana thylakoids occur only at the lowest cut-off wavelengths of 280 and 275 nm. The structural alterations end up in a more or less complete desintegration of grana and stroma thylakoids with the remaining membraneous structures appearing in negative staining thus indicating drastic changes in membrane composition. Photosynthetic activity determined by chlorophyll fluorescence (ratio of variable to maximal fluorescence) and oxygen evolution responded more sensitively to UV-B irradiation. With decreasing UV cut-off wavelengths and prolonged incubation a decrease of photochemistry of PS II occured reaching its lowest values after 60 min at 275 and 280 nm. Oxygen production was even maintained under strong UV irradiation with a cut-off wavelenght of 275 nm up to 15 min. With prolonged UV-B treatment any activity was lost. HPLC separations of pigments exhibited the appearance of break-down products (mainly derivatives of chl b and chl a) with decreasing cut-off wavelength and increasing exposure time. The xanthophyll cycle pigments seemed to be unaffected at least for an irradiation period of 60 to 90 min at low UV cut-offs. Possible mechanisms of UV stress avoidance or protection are discussed with regard to the varying altitudes of the natural habitats of the algae.
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    Electronic Resource
    Ultrastructural study of the proboscis endothelium of Riseriellus occultus (Nemertea, Heteronemertea) (1997)
    Springer
    Hydrobiologia 365 (1997), S. 121-127 
    Details
    ISSN: 1573-5117
    Keywords: Riseriellus occultus ; Heteronemertea ; Proboscis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined with transmission electron microscopythe epithelial layer exposed to the rhynchocoel fluidof the proboscis in the heteronemertine Riseriellus occultus. This epithelium is organized asa monociliated, pseudostratified myoepitheliumconsisting of two cell types: apically situatedmonociliated supportive cells and subapical myocyteslacking cilia. The low supportive cells form acontinuous adluminal sheet and reach with numerouscytoplasmic processes into the extracellular matrix;these cells are characterized by numerous, irregularlyshaped, apical folds projecting into the rhynchocoelfluid, delimiting broad extracellular spaces. Theauthors suppose that both apical and basal folds couldaccommodate stretching of the endothelium when theproboscis is everted. The apical folds of thesupportive cells increase the interface of these withthe rhynchocoel fluid; this feature, together with thepresence of pinocytotic vesicles in such cells,suggest that they could be involved in the exchange ofsubstances between the rhynchocoel fluid and theproboscis. The myocytes are scattered singly withinthe monociliated pseudostratified myoepithelium. Theyare situated between the supportive cells and thesubjacent extracellular matrix. Basement membraneseparating both cells types is lacking. Myofibrillarparts protrude basally from the myocyte somata. Themyofibrillar parts lie in direct apposition to theextracellular matrix, and are oriented circular to thelongitudinal axis of the proboscis. We consider themyocytes to be intra-epithelial, myoepithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003101703985
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