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  • Ultrastructure  (109)
  • Springer  (109)
  • American Institute of Physics
  • Nature Publishing Group
  • 1990-1994  (31)
  • 1980-1984  (78)
  • 1993  (31)
  • 1981  (78)
Collection
Keywords
Publisher
  • Springer  (109)
  • American Institute of Physics
  • Nature Publishing Group
  • Wiley-Blackwell  (7)
Years
  • 1990-1994  (31)
  • 1980-1984  (78)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of differentiating preameloblasts from tooth germs of the permanent dentition ofMacaca mulatta andMacaca arctoides (1981)
    Springer
    Calcified tissue international 33 (1981), S. 603-618 
    Details
    ISSN: 1432-0827
    Keywords: Preameloblasts ; Tooth germs ; Monkey ; Enamel ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cytodifferentiation of inner enamel epithelium and the adjacent connective tissue from the tip of the cervical loop to the initiation of enamel elaboration in twoMacaca species was examined. Ten- to twelve-month-old specimens were fixed by perfusion and the permanent tooth buds were prepared for transmission electron microscopy. At the cervical loop proper, inner enamel epithelium cells have lobed nuclei, a paucity of cytoplasm, and wide extracellular spaces; the basal lamina facing the dental papilla is straight. With increasing distance from the tip of the cervical loop, the following changes occur gradually: (a) preameloblasts elongate from 15 to 45 µm, and their organelles, particularly mitochondria and profiles of rough endoplasmic reticulum, become more numerous; (b) extracellular spaces decrease between preameloblasts starting at the basal (infranuclear) end; (c) the basement membrane becomes convoluted and associated with aperiodic fibers; (d) preodontoblast projections penetrate the aperiodic fibers; (e) collagen fibers subjacent to the basement membrane increase in density, with particularly thick fibers paralleling the aperiodic fibers. These modifications occur within three-fourths of the distance from the tip of the cervical loop to the mineralization front. The condensation of preodontoblasts is followed immediately by predentin synthesis. Concomitantly, the basement membrane breaks down and the aperiodic fibers are engulfed by preameloblasts. Preameloblast projections penetrate junctional predentin, contact mineralized dentin, and enamel synthesis ensues. At this stage the ameloblast is 45 µm long, the nucleus is central or basal, the Golgi apparatus has migrated apically, but the Tomes' process has not yet formed. The results indicate that odontogenesis inMacaca monkeys more closely resembles human odontogenesis than does that in the murine rodents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409498
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural study ofCryptococcus neoformans by quick-freezing and deep-etching method (1993)
    Springer
    Mycopathologia 121 (1993), S. 133-141 
    Details
    ISSN: 1573-0832
    Keywords: Capsule ; Cryptococcus neoformans ; Deep-etching ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The three-dimensional ultrastructure ofCryptococcus neoformans was studied by quick-freezing and deep-etching (QF-DE) method.C. neoformans, strain CDC551, was cultured on agar. The viable yeast cells (107 cells) were inoculated into each mouse from the tail vein. Three weeks after the inoculation, the brains of the mice were perfused with fixatives, quickly frozen, freeze-fractured, deeply etched and rotary shadowed with platinum and carbon. In addition, the viable cells ofC. neoformans on agar were picked up and quickly frozen, and replica membranes were prepared as described above. The ultrastructure ofC. neoformans was three-dimensionally demonstrated by the QF-DE method. The capsule was composed of fine meshworks of microfibrils (10–13 nm in diameter), which were directly attached to the cell walls. The capsule of the in vivo yeasts (yeast cells in the brain lesion) was thicker than that of the in vitro yeasts (yeast cells on agar culture). At the outer part of the cell wall, a particle-accumulating layer was observed. This layer in vivo was thicker than that in vitro. Occasionally, the yeast cells were ingested by phagocytes in the mouse brain. Although the cytoplasm of such yeast cells was destroyed, the capsular meshworks were well preserved. The ultrastructure of the capsule was the same both in cultured and phagocytized yeasts in the cystic lesions of the brains. This lack of morphological changes of the capsular meshworks suggests that they are resistant to the digestion by phagocytes. This stability of capsular structures may provide one of the important pathogenic factors in cystic lesions byC. neoformans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01104068
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  • 3
    Electronic Resource
    Electronic Resource
    Mayflies (ephemeroptera), the most “primitive” winged insects, have telotrophic meroistic ovaries (1993)
    Springer
    Development genes and evolution 203 (1993), S. 18-27 
    Details
    ISSN: 1432-041X
    Keywords: Oogenesis ; Germ line cell cluster ; Oocyte determination ; Ultrastructure ; Mayflies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germ line cell cluster formation in ovarioles of three different stages, each from a different mayfly species, was studied using ultra-thin serial sectioning. In the analysed ovariole of Cloeön sp., only one linear, zigzag germ line cell cluster was found, consisting of sibling cells connected by intercellular bridges which represent remnants of preceding synchronized mitotic cycles followed by incomplete cytokinesis. A polyfusome stretched through all sibling cells. At the tip of the ovariole, cytokinesis occurred without preceding division of nuclei; thus, intercellular bridges were lined up but the remaining cytoplasm between the bridges had no nuclei. The analysed Siphlonurus armatus vitellarium contained five oocytes at different stages of development. Each oocyte in the vitellarium was connected via a nutritive cord to the linear cluster of its sibling cells in the terminal trophic chamber. Each cluster had the same architecture as was found in Cloëon. The 3-dimensional arrangement and distribution of closed intercellular bridges strongly suggest that all five clusters are derived from a single primary clone. The position of oocytes within each cluster is random. However, each oocyte is embraced by follicular or prefollicular cells whilst all other sibling cells are enclosed by somatic inner sheath cells, clearly distinguishable from prefollicular cells. In the analysed ovariole of Ephemerella ignita, two small linear clusters were found in the tropharium beside two single cells, two isolated cytoplasmic bags with intercellular bridges but no nuclei, and some degenerating aggregates. One cluster was still connected to a growing oocyte via a nutritive cord. In all species the nurse cells remained small and no indications of polyploidization were found. We suggest that this ancient and previously unknown telotrophic meroistic ovary has evolved directly from panoistic ancestors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00539886
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural expression of cytoplasmic male sterility in sugar beet (Beta vulgaris L.) (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 22-32 
    Details
    ISSN: 1432-2145
    Keywords: Cytoplasmic male sterility ; Ultrastructure ; Mitochondria morphometry ; Beta vulgaris L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of microspore mother cells (MMC) and tapetum in male-fertile and male-sterile anthers of Beta vulgaris L. was compared at the electron microscope level. These studies were complemented by morphometric analyses of mitochondria in both tissues through successive stages of microsporogenesis. The earliest irregularities in the ultrastructure of male-sterile anthers were noted within the tapetum at the tetrad stage. These disturbances were initially expressed by a slight reduction in mitochondrial size and the appearance of concentric configurations of endoplasmic reticulum. As development proceeded, a further decrease in mitochondrial size become more conspicuous and was accompanied by a reduction in ribosome population and a failure of the tapetum to produce Ubisch bodies. This failure to produce Ubisch bodies is reflected in the underdevelopment of sterile microspore exine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227579
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  • 5
    Electronic Resource
    Electronic Resource
    Megaspore development in Selaginella. I. “Wicks”, their presence, ultrastructure, and presumed function (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 98-107 
    Details
    ISSN: 1432-2145
    Keywords: Selaginella ; Megaspore ; Exospore ; Ultrastructure ; Tapetal cells ; Plasmodesmata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Structures have been found in the locular space between the tapetal cells and megaspores in Selaginella argentea and S. kraussiana that enter the megaspore wall and extend to the plasma membrane of the megaspore cytoplasm. We have called these structures “wicks”. Unless special fixation procedures are used wicks are either very poorly preserved or not apparent. Wicks appear to be routes for the transport of materials from the tapetum to developing megaspores. The entry of the wicks into the megaspore wall and their passage throughout the wall implies that the megaspore wall of Selaginella is a three-dimensional mesh-work of inter-connecting spaces. Wicks have several macromolecular-sized subunits, and the results of our histochemical reactions indicated the presence of glycoprotein and/or mucopolysaccharide. X-ray microanalysis of the S. convoluta exospore showed that silicon is present in rod-shaped structures between units of the exospore in mature megaspores. Because of the size and form of the structures between the exospore units we consider that they are remnants of wicks stabilized by silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227654
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical agents that inhibit pollen development: effects of the phenyl-cinnoline carboxylates SC-1058 and SC-1271 on the ultrastructure of developing wheat anthers (Triticum aestivum L. var Yecora rojò) (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 108-212 
    Details
    ISSN: 1432-2145
    Keywords: Wheat pollen ; Chemical hybridizing agents ; Male sterility ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phenylcinnoline carboxylate compounds SC-1058 and SC-1271 cause complete male sterility in wheat when applied at suitable dosages at the pre-meiotic stage of anther development. Anthers from treated and untreated plants were compared using light and electron microscopy from the pre-meiotic stage through the formation of nearly mature pollen. Overall anther development is gradually slowed in treated plants and pollen development is generally arrested in the late prevacuolate or early vacuolate microspore stage, although the first pollen mitosis does sometimes occur. The sporopollenin-containing exine walls are thinner, and show abnormally developed foot and tectum layers with sparse connecting baculi. Microspore cytoplasm degenerates and the cells eventually collapse. At the early, prevacuolate, free microspore stage treated tapetal cells hypertrophy, expanding into the locule. They contain abnormally large vacuoles that appear to form from the fusion of secretory vesicles, and some vacuoles contain electrondense deposits. The sporopollenin-containing orbicular wall and Ubisch bodies are retarded in their development and are structurally deformed. Acetolysis of whole anthers and of thick sections shows that the sporopollen-in-containing structures of treated materials are greatly reduced in thickness and are less rigid than in the control. We conclude that application of these compounds causes interference with the secretory function of tapetal cells which supplies sporopollenin cell-wall polymers to the exine of the microspores and to the tapetal orbicular wall and associated Ubisch bodies. Interference with the tapetal secretion of other nutrients required for microspore development is strongly suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227655
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  • 7
    Electronic Resource
    Electronic Resource
    The embellum: a newly defined structure in the grass ovule (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 191-198 
    Details
    ISSN: 1432-2145
    Keywords: Micropyle ; Transfer cells ; Ultrastructure ; Nucellus ; Poaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several kinds of outgrowth from the grass ovule are known. Attention is focused here on one outgrowth that occurs within or around the micropyle and is of nucellar origin. Grass species in which it is currently known to occur are listed and examples of variants briefly described. Attention is concentrated upon Pennisetum, where the cell structure is described in detail with a series of electron photomicrographs. The tissue representing an aggregation of these transfer cells is newly named with the term ‘embellum’, and its significance for pollen tube growth is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228648
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  • 8
    Electronic Resource
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    Ultrastructural changes in the appendix of the Sauromatum guttatum inflorescence during anthesis (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 153-170 
    Details
    ISSN: 1432-2145
    Keywords: Appendix ; Sauromatum guttatum ; Ultrastructure ; Mitochondrion ; Amyloplast ; Peroxisome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the epidermal and sub-epidermal cells of the appendix of the Sauromatum guttatum inflorescence reveals developmental changes during anthesis. These changes precede, and probably make possible, heat and odor production. Two days before D-day (the day of heat production and inflorescence-opening) the mitochondria of the epidermis divide; apparent division of the amyloplasts was observed at the same time. The presence of lipid bodies and peroxisomes in the epidermis was clearly evident. On D-day, the epidermis becomes a continuous layer in which the cell walls separating two adjacent cells disappear. At the same time, in the sub-epidermal cells, the mitochondria and the amyloplasts undergo division. The mitochondria become electron-dense, and their DNA is clearly visible. On that day, lipids as well as starch are being depleted. The peroxisomes change in structure every day, from D-2 to D-day. It has also been demonstrated by histochemical techniques that during anthesis the activity of cytochrome c oxidase (3,3-diaminobenzidine as a substrate) decreases whereas the activity of NADH dehydrogenase [tetrazolium salts: nitro-blue tetrazolium chloride (NBT) or neotetrazolium chloride (NT) in the presence of NADH], increases. Oxygen consumption of isolated mitochondria from the D-day appendix was inhibited in the presence of the two tetrazolium salts to a different degree: oxidation of NADH in the presence of NBT was the most sensitive to inhibition, more so than the oxidation of malate and succinate. NT was less effective as an inhibitor in the presence of those three respiratory substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228644
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  • 9
    Electronic Resource
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    Ultrastructural events and kinetics of microcyst germination in the myxomycete Didymium iridis (1981)
    Springer
    Archives of microbiology 128 (1981), S. 384-389 
    Details
    ISSN: 1432-072X
    Keywords: Didymium iridis ; Microcyst ; Excystment ; Germination ; Ultrastructure ; Mycetozoa ; Myxomycetes ; Myxamoeba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microcysts of the myxomycete Didymium iridis were induced to excyst by transfer to 5mM potassium phosphate buffer. After 1 h in suspension, 90% of the microcysts had germinated into myxamoebae distinguishable by phase contrast microscopy and staining with Lugol's iodine. Both pH and osmolarity affected the kinetics of excystment. The rate and extent of excystment were decreased by cycloheximide but remained unaffected by actinomycin D, suggesting a requirement for protein synthesis but not RNA synthesis. Initially, the outer wall layers separated from the inner layer, which gradually expanded and loosened. The protoplast rehydrated and reverted to a vegetative morphology. Excysting cells were characterized by nucleolar inclusions, changes in the nuclear envelope and plasma membrane, appearance of ringed cisternal elements and microbodies in the cytoplasm, and formation of a densely fibrous zone adjacent to the site of emergence. Excysting populations have been classified into characteristic stages: mature, initiated, swollen, and pre-emergent microcysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405917
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  • 10
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    The effects of nitrogen limitation on the ultrastructure of the cyanobacterium Agmenellum quadruplicatum (1981)
    Springer
    Archives of microbiology 130 (1981), S. 204-212 
    Details
    ISSN: 1432-072X
    Keywords: Agmenellum quadruplicatum ; Nitrogen starvation ; Ultrastructure ; PATO poststain ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nitrogen limitation on the ultrastructure of the unicellular cyanobacterium, Agmenellum quadruplicatum, were studied by thin sectioning transmission electron microscopy. Nitrogen became limiting for growth 14–15 h after transfer to nitrogen-limiting medium, but cultures retained full viability for at least 45 h. The c-phycocyanin: chlorophyll a ratio and cellular nitrogen content of the culture dropped rapidly after 14–15 h, as a progressive deterioration of major cell structures took place. Phycobilisomes were degraded first, followed by ribosomes and, then, thylakoid membranes. These structures were virtually depleted from the cells within 26 h. Intracellular polysaccharide accumulated in place of the normal cell structures throughout this period. Nitrogen limitation did not affect polyphosphate bodies, carboxysomes, lipid granules, the cell envelope, or the extra-cellular glycocalyx. All of the ultrastructural changes resulting from nitrogen limitation were reversed upon addition of nitrate to a starved culture. Most cell structures were restored within 3 h, and restoration was complete within 9 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00459520
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  • 11
    Electronic Resource
    Electronic Resource
    Arthrobacter P 1, a fast growing versatile methylotroph with amine oxidase as a key enzyme in the metabolism of methylated amines (1981)
    Springer
    Archives of microbiology 129 (1981), S. 72-80 
    Details
    ISSN: 1432-072X
    Keywords: Arthrobacter ; Facultative methylotroph ; Amine oxidase ; Catalase ; RuMP cycle of formaldehyde fixation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A facultative methylotrophic bacterium was isolated from enrichment cultures containing methylamine as the sole carbon source. It was tentatively identified as an Arthrobacter species. Extracts of cells grown on methylamine or ethylamine contained high levels of amine oxidase (E.C. 1.4.3.) activity. Glucose- or choline-grown cells lacked this enzyme. Oxidation of primary amines by the enzyme resulted in the formation of H2O2; as a consequence high levels of catalase were present in methylamine-and ethylamine-grown cells. The significance of catalase in vivo was demonstrated by addition of 20 mM aminotriazole (a catalase inhibitor) to exponentially growing cells. This completely blocked growth on methylamine whereas growth on glucose was hardly affected. Cytochemical studies showed that methylamine-dependent H2O2 production mainly occurred on invaginations of the cytoplasmic membrane. Assimilation of formaldehyde which is generated during methylamine oxidation was by the FBP variant of the RuMP cycle of formaldehyde fixation. The absence of NAD-dependent formaldehyde and formate dehydrogenases indicated the operation of a non-linear oxidation sequence for formal-dehyde via hexulose phosphate synthase. Enzyme profiles of the organism grown on various substrates suggested that the synthesis of amine oxidase, catalase and the enzymes of the RuMP cycle is not under coordinate control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00417184
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  • 12
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    Identification of Naemacyclus minor hyphae within needle tissues of Pinus sylvestris by immunoelectron microscopy (1993)
    Springer
    Archives of microbiology 160 (1993), S. 265-272 
    Details
    ISSN: 1432-072X
    Keywords: Pinus sylvestris ; Naemacyclus minor ; Immunocytochemical identification ; Ultrastructure ; Plant-fungus interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultural investigations revealed that Naemacyclus minor, Lophodermium seditiosum and Cenangium ferruginosum were the most frequent colonizers of asymptomatic and symptomatic Pinus sylvestris needles. Since ultrastructural observations showed that morphological features were not suitable to differentiate hyphae of N. minor from hyphae of other isolates, the on-section immunogold labelling technique was applied in combination with an anti-N. minor specific immunoserum. The specificity of this serum was tested against culture hyphae of all isolates. Anti-N. minor specific immunoserum was then used to identify N. minor hyphae in thin sections of green P. sylvestris needles. The infection loci identified were restricted to small tissue areas located in the vicinity of stomata. In the hypodermis, hyphae and endocell-containing hyphae were located within the lumina of host cells but outside the protoplast. The growth of hyphae from cell to cell occurred through pits. The hyphae spreat into the mesophyll intercellularly and continued with the intracellular colonization of moribund and dead mesophyll cells in a later stage of infection. The observed host-parasite interactions at cellular and ultrastructural level are discussed in connection with the still controversial interpretation of the pathogenicity of N. minor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292075
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  • 13
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    Ultrastructure of Bacillus pulvifaciens (1993)
    Springer
    Archives of microbiology 159 (1993), S. 114-118 
    Details
    ISSN: 1432-072X
    Keywords: Bacillus pulvifaciens ; Vegetative cells ; Spotes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of vegetative cells and spores of Bacillus pulvifaciens was studied by CTEM and SEM methods. The vegetative cells are rods, 1.6–4.5 μm long and 0.4–0.6 μm wide, exhibiting typical ultrastructural features of Gram-positive bacteria. The spores are of ellipsoidal shape, 0.6×1.2 μm in size, with six longitudinal ribs reaching up to 130 nm in height. There are satelite ribs on both sides of the longitudinal ribs, reaching up to 20 nm in height. Between the longitudinal ribs, additional transversal ribs were observed in SEM. A special tubular layer, separating the outer and inner coat of the spores, was revealed in ultrathin sections. This layer seems to be a typical ultrastructural feature of Bacillus pulvifaciens spores.
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    URL: http://dx.doi.org/10.1007/BF00250269
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  • 14
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    Development of quasi-multicellular bodies of Treponema denticola (1993)
    Springer
    Archives of microbiology 160 (1993), S. 206-213 
    Details
    ISSN: 1432-072X
    Keywords: Treponema denticola ; Spirochetes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of quasi-multicellular bodies of Treponema denticola was analysed using different electron microscopical methods. These bacteria could develop four different conformations: (i) normal helical forms; (ii) twisted spirochetes, forming plaits; (iii) twisted spirochetes, forming club-like structures; (iv) spherical bodies in different size. Treponemes within spherical bodies, plaits, and clubs proved to be enclosed in a common outer sheath in which the normal arrangement of their axial flagella was lost. The development of the quasi-multicellular bodies starting from the monoforme spirochetes was elucidated and this morphogenetic process is illustrated by a schematic drawing. Factors which might be involved in the induction of the structures are discussed and their possible pathogenetic importance is considered.
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    URL: http://dx.doi.org/10.1007/BF00249126
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  • 15
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    The pineal gland of nocturnal mammals (1981)
    Springer
    Cell & tissue research 216 (1981), S. 253-271 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Cell populations ; Bat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the pineal gland of the pipistrelle bat two different populations of pinealocytes and glial cells were observed electron microscopically. The pinealocytes of populations I and II differ in their content of metabolically active cell organelles. In the pinealocytes of population I, granular vesicles originating from the Golgi apparatus were found in the perikaryon and especially in the endings of the pinealocyte processes. Granular vesicles appeared to be more numerous in hibernating nulliparous females. The pinealocytes of population II are characterized by the presence of small cytoplasmic vacuoles, probably originating from cisternae of the granular endoplasmic reticulum and containing flocculent material of moderate electron density. The classification of the pinealocytes belonging to population II is discussed.
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    URL: http://dx.doi.org/10.1007/BF00233619
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  • 16
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    The fine structure of the compound eye of the African armyworm moth, Spodoptera exempta walk. (Lepidoptera, Noctuidae) (1981)
    Springer
    Cell & tissue research 216 (1981), S. 333-347 
    Details
    ISSN: 1432-0878
    Keywords: Insect eye ; Retina ; Ultrastructure ; Moth ; Spodoptera exempta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology of the compound eye of the noctuid moth Spodoptera exempta was investigated by electron microscopy. This eucone superposition eye is composed of about 8000 ommatidia. Each ommatidium is surrounded by six secondary pigment cells showing pigment movement according to the state of adaptation. It contains four crystalline cone cells forming together a crystalline cone and tract, two primary pigment cells, which encompass the crystalline cone, and usually eight retinula cells. On the basis of their rhabdomeric structure, three types of retinula cells can be distinguished. According to the structure of the rhabdom, two types of ommatidia are found in different regions of the eye. The rhabdom of the lobed type, providing more than 80% of ommatidia, is composed of V-shaped rhabdomeres with fanwise arranged microvilli. The rhabdom of the square type, found in a small area in the dorsal region of the eye, consists of triangular rhabdomeres with parallel microvilli. The functional significance of this difference is discussed.
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    URL: http://dx.doi.org/10.1007/BF00233623
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  • 17
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    Avian epidermis contains ATPase- and Ia-positive Langerhans-like cells (1993)
    Springer
    Cell & tissue research 271 (1993), S. 103-106 
    Details
    ISSN: 1432-0878
    Keywords: Skin ; Langerhans cell ; ATPase-histochemistry ; Ultrastructure ; Ia antigen ; Four avian species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The occurrence of cells resembling mammalian Langerhans cells in the avian epidermis was studied by ATPase histochemistry, Ia immunoreactivity and electron microscopy. The existence of MHC class II antigen-(Ia) expressing, ATPase-positive dendritic cells, which are ultrastructurally similar to mammalian Langerhans cells except for the absence of Birbeck granules, was demonstrated. These cells may be a basic component of the immune system of birds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297547
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  • 18
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    Development of the diffuse endocrine system in the chicken proventriculus (1993)
    Springer
    Cell & tissue research 271 (1993), S. 107-113 
    Details
    ISSN: 1432-0878
    Keywords: Proventriculus ; Endocrine ontogenesis ; Ultrastructure ; Regulatory peptides ; Immunocytochemistry ; Silver impregnations ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of endocrine cells in the chicken proventriculus has been investigated using light-and electron-microscopy in conjunction with silver and immunocytochemical techniques. The first morphologically detectable endocrine cells were found in 5-day-old embryos by electron microscopy. From the 9th to the 13th day, endocrine cells in contact with the lumen of the organ could be detected both by electron and light (silver impregnation) microscopy. The number of open-type endocrine cells progressively decreased and the number of closed-type increased after this stage. Until the 16th day, endocrine cells were located exclusively in the luminal epithelium, but afterwards they appeared in progressively greater numbers in the compound glands. After hatching, long cytoplasmic processes could be seen in the endocrine cells. Immunoreactivities to regulatory substances appeared in the following order: serotonin (day-14), avian pancreatic polypeptide, glucagon and somatostatin (day-16), bombesin and neurotensin (day-18), and finally, met-enkephalin (day-21).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297548
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    Immunocytochemical effects of thyroxine stimulation on the adenohypophysis of dwarf (dw) mutant mice (1993)
    Springer
    Cell & tissue research 274 (1993), S. 579-585 
    Details
    ISSN: 1432-0878
    Keywords: Thyroxine ; Pituitary gland, pars distalis ; Immunocytochemistry ; Ultrastructure ; Mouse (Snell dwarf)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effects of dietary thyroxine on the immunoreactivity of cells in the pars distalis of the adenohypophysis in dwarf (dw/dw) mice were determined by ultrastructural immunocytochemistry. In nontreated dwarfs only adrenocorticotropic hormone (ACTH) cells and luteinizing hormone (LH) cells showed positive reactions to their respective antibodies, whereas no cells showed immunoreactivity to antibodies to growth hormone (GH), thyroid-stimulating hormone (TSH), or prolactin (Prl). In dwarfs supplemented postnatally with dietary thyroxine for 9 wks, the treatment failed to produced immunoreactive GH, TSH or Prl cells. However, LH cells became more prominent and fully developed, with denser concentrations of immunoreactive particles overlying the secretory granules than occurred in nontreated dwarfs. In thyroxine-treated dwarfs, ACTH cells were similar in ultrastructural features and immunoreactivity to those in nontreated dwarfs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314556
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    Rhythmic contractions of the ampullar epidermis during metamorphosis of the ascidian Molgula occidentalis (1981)
    Springer
    Cell & tissue research 216 (1981), S. 293-312 
    Details
    ISSN: 1432-0878
    Keywords: Ascidians ; Metamorphosis ; Attachment organs ; Ultrastructure ; Rhythmic contractions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ampullae of Molgula occidentalis are hollow, tubular extensions of the epidermis. They are ensheathed by a secreted tunic. When they grow out shortly after settlement, the ampullae spread the tunic over the substratum to form a firm attachment for the sessile juvenile. A simple squamous epithelium forms the thin ampullar walls. A glandular, simple columnar epithelium forms the distal tip of each ampulla. The glandular cells probably secrete the adhesive that attaches the tunic to the substratum. Repetitive, peristaltic contractions pass from the base to the distal end of each ampulla. Microsurgery, time-lapse cinemicrography and TEM have been used to analyze this phenomenon. The contractions are mediated by a layer of 4–8 nm microfilaments in the base of the ampullar epithelium. Each juvenile has 7–9 ampullae which contract at different frequencies. Isolated ampullae continue to contract normally for several days. Thus each ampulla has an intrinsic rhythm. Microsurgical experiments suggest that there is no specific region within an ampulla with unique pacemaker properties. It is proposed that communication via gap junctions allows the coordination of ampullar cells into a well organized peristaltic wave.
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    URL: http://dx.doi.org/10.1007/BF00233621
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    Biphasic effect of ACTH on growth of rat adrenocortical cells in primary culture (1993)
    Springer
    Cell & tissue research 271 (1993), S. 169-176 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Differentiation ; Tissue culture ; Proliferation ; Ultrastructure ; Steroids ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proliferation rate of differentiating fetal rat adrenocortical cells was studied in primary culture. In this system, stimulation with ACTH induces differentiation of zona glomerulosa-like cortical cells into zona fasciculata-like cells. Incorporation of bromodeoxyuridine (BrdU) was studied immunocytochemically by use of anti-BrdU antibody, and the proliferation rate was counted from the monolayer colonies of adrenocortical cells. After 21 days of cultivation in the absence of ACTH, the proliferation rate of zona glomerulosa-like cells was 10%. The rate slowly declined to 1% at the age of 100 days during continuous cultivation in the absence of ACTH. Stimulation with ACTH induced a strong inhibition in the proliferation rate (down to 2% during the first 24 h). Treatment with ACTH during the following 48 h led to an extremely intense proliferation of adrenocortical cells at a proliferation rate of 25%. Continuous treatment with ACTH up to 100 days led to a persistent growth of adrenocortical cells, and a proliferation rate over 2-fold higher than in control cells cultivated in the absence of ACTH. Thus, ACTH is the principal growth-promoting factor also in vitro, as has been found in in vivo studies. This growth effect is mediated by a biphasic course; at the beginning of differentiation the effect is inhibitory and is followed by a persistent stimulation of the growth of adrenocortical cells.
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    URL: http://dx.doi.org/10.1007/BF00297555
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    Ultrastructure and morphometry of testicular Leydig cells and the interstitial components correlated with testosterone in aging rats (1993)
    Springer
    Cell & tissue research 271 (1993), S. 241-255 
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    ISSN: 1432-0878
    Keywords: Leydig cell ; Testis ; Interstitium ; Aging ; Ultrastructure ; Morphometry ; Testosterone ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ultrastructure of testicular interstitium in young and aged adult rats was analysed using morphometric methods, and the plasma testosterone concentration was measured. With increasing age there was an augumentation in the volume of collagen fibrils in the intercellular matrix and in blood vessels. During the aging process (approximately two years) the average volume of the Leydig cell decreased from 1364 μm3 to 637 μm3, but the number of Leydig cells in paired testes increased from 53x106 to 113x106. The absolute volume of smooth surfaced endoplasmic reticulum (SER) per Leydig cell amounted in aged rats to 78% of that in young adult rats. The total amount of SER in paired testes increased by 62% with aging. The present analysis suggests that the ability of SER to maintain peripheral testosterone concentration decreases with age. In young adult rats the absolute volume of peroxisomes per Leydig cell correlated significantly with the concentration of testosterone in blood and also with the absolute volume of SER per Leydig cell. These results combined with ultrastructural observations of close apposition of peroxisomes and SER suggest that peroxisomes have a role in testosterone secretion by Leydig cells.
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    URL: http://dx.doi.org/10.1007/BF00318610
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    Effect of omeprazole-evoked hypergastrinemia on ultrastructure of enterochromaffin-like cells in the stomach of portacaval-shunted rats (1993)
    Springer
    Cell & tissue research 272 (1993), S. 71-77 
    Details
    ISSN: 1432-0878
    Keywords: Enterochromaffin-like cells ; Hypergastrinemia ; Hypertrophy ; Ultrastructure ; Omeprazole ; Portacaval shunt ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-producing enterochromaffinlike (ECL) cells in the acid-producing portion of the rat stomach responded to long-standing hypergastrinemia (omeprazole treatment daily for 8–10 weeks) with hypertrophy (and hyperplasia) and with a reduced number of granules and vesicles per unit cytoplasm. There was a reduction in the ratio of electron-dense granules versus vesicles and an increase in the profile diameter of the vesicles. Also, portacaval shunting (PCS) induced changes in the ECL cells, manifesting (i) as an increase in cell number and size, and (ii) as a reduced number of granules and vesicles per unit area. The cytoplasmic granules and vesicle profiles were enlarged, and the ratio of granules versus vesicles was reduced. The combination of PCS and long-standing hypergastrinemia (omeprazole treatment) produced a greatly enhanced ECL cell hypertrophy (and hyperplasia) and a marked reduction in the number of granules. The ratio of granules versus vesicles was markedly reduced while the profile diameters of both granules and vesicles were increased. The relative predominance of very large vesicles (vacuoles) was a prominent feature of the ECL cells in these rats.
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    URL: http://dx.doi.org/10.1007/BF00323572
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    Ultrastructure of free nerve endings in respiratory and squamous epithelium on the rat nasal septum (1993)
    Springer
    Cell & tissue research 274 (1993), S. 329-335 
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    ISSN: 1432-0878
    Keywords: Intraepithelial axons ; Free nerve endings ; Nasal mucosa ; Ultrastructure ; Enzyme histochemistry ; Immunocytochemistry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of nerve fibres in the mucosa of the nasal septum of the rat was investigated by means of transmission electron microscopy on transverse and tangential ultrathin sections. Near the basement membrane of respiratory and squamous epithelium, a rather dense network of unmyelinated nerve fibres occurs. Some fibres in the respiratory epithelium ascend between the epithelial cells to reach up to the tight junctions. These fibres appeared in transverse sections to end as hooks or boutons, sometimes with branches. These shapes resemble the free nerve endings that are considered to act as nociceptors. The small intraepithelial fibres, with diameters of about 0.5–1 μm, contain both dense granules and clear vesicles comparable to synaptic vesicles. Substance P was found in dense granules in basal fibres; vasoactive intestinal peptide was absent throughout the epithelium. Acetylcholinesterase activity was observed closely associated with the basal fibres; the apical fibres showed little if any activity. Membrane specializations pointing to an efferent function as well as structures usually associated with mechanoreceptive functions were lacking in both respiratory and squamous epithelium.
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    URL: http://dx.doi.org/10.1007/BF00318751
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    The effects of gonadectomy and testosterone treatment on the Harderian gland of the green frog, Rana esculenta (1993)
    Springer
    Cell & tissue research 273 (1993), S. 201-208 
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    ISSN: 1432-0878
    Keywords: Harderian gland ; Castration ; Testosterone ; Ultrastructure ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effects of gonadectomy and testosterone treatment on the fine structure of the Harderian gland in male and female green frogs were investigated in different periods of the year. Gonadectomy, carried out when the glands are in the lowest secretory phase (September), causes degenerative changes consisting of a reduction of the rough endoplasmic reticulum, the appearance of autolysosomes, and an increase of nuclear heterochromatin. These effects can be prevented by testosterone treatment. No castration effects are found during the recovery (November) and enhancement (April-May) phases of secretory activity. The results suggest that the frog Harderian gland's sensitivity to testosterone changes during the annual cycle. The androgen dependence of the Harderian gland is correlated with the presence of androgen receptors in both male and female forgs.
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    URL: http://dx.doi.org/10.1007/BF00312821
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    Secretory granules of B-cells in the synovial membrane (1981)
    Springer
    Cell & tissue research 216 (1981), S. 131-141 
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    ISSN: 1432-0878
    Keywords: Synovial membrane ; Secretory granules ; Ultrastructure ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural and cytochemical studies have been made on secretory granules of B-cells (fibroblast-like cells) in the knee-joint synovium. The secretory granules were membrane-bounded spherical or slightly elongated bodies, 150 to 350 nm (average 230 nm) in diameter and had a homogenous matrix with several cores. These granules were found in B-cells of all animal species examined; they were numerous in mice and rats, and few in guinea pigs, rabbits and man. Ultrastructural and cytochemical examinations revealed that the Golgi apparatus was involved in the formation of the secretory granules. Unlike lysosomes, they showed no acid phosphatase activity. The granule matrix was positively stained by Thiéiy's periodic acid-thiocarbohydrazidesilver proteinate technique, and the cores were digested by protease. These findings suggest that the granule matrix contains mucopolysaccharide(s) and/or glycoprotein(s) and the core material is largely proteinaceous in nature.
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    URL: http://dx.doi.org/10.1007/BF00234549
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    Effects of norepinephrine and dibutyryl adenosine 3′, 5′-cyclic monophosphate on the ultrastructure of pineal cells in monolayer culture (1981)
    Springer
    Cell & tissue research 216 (1981), S. 181-191 
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    ISSN: 1432-0878
    Keywords: Pineal gland ; Monolayer culture ; N-acetyl transferase ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To determine how neural influences control the function of the pineal gland, morphological and biochemical relationships after pharmacological treatment have been studied in rat pineal cells in monolayer cultures. Norepinephrine (NE) and dibutyryl cyclic 3′,5′-adenosine monophosphate (dBcAMP) treatment of cells that had been in culture for 5 and 21 days produced a stimulation in the enzyme activity of serotonin N-acetyl transferase, an enzyme important in indole synthesis. NE and dBcAMP also produced morphological changes which were dependent on the time of cells in culture. When 5 day-cultures were treated with NE and dBcAMP, light and dark cells were noted and endoplasmic reticulum increased and became more organized. Only dBcAMP treatment at 5 days produced an increase in dense granules and an elongation of cytoplasmic processes. Treatment of 21 day-cultures with dBcAMP also produced an increase in cytoplasmic processes while treatment with NE produced an increase in the synaptic ribbons and clear vesicles within the processes.
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    URL: http://dx.doi.org/10.1007/BF00234553
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    Role of estrogen and androgen in maintaining the preovulatory follicle (1981)
    Springer
    Cell & tissue research 216 (1981), S. 615-624 
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    ISSN: 1432-0878
    Keywords: Rat ; Preovulatory follicle ; Ultrastructure ; Estrogen ; Androgen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of Nitromifene citrate (CI 628), an antiestrogen, and Flutamide, an antiandrogen, on the ultrastructure and viability of the preovulatory follicle and granulosa cells were examined both in vivo and in vitro. In vivo administration of either antihormone induced degeneration within the granulosa cells. In some of the affected granulosa cells, the nuclear material was condensed while the cytoplasm and associated organelles were unaltered. In others, the density of the cytoplasm was reduced, the smooth endoplasmic reticulum was dilated but the nucleus remained unaltered. In vitro, either antihormone reduced granulosa-cell viability but the granulosa cells were twenty times more sensitive to CI 628 than to Flutamide. In addition, exposure to CI 628 induced nuclear condensation without affecting the cytoplasm, while Flutamide induced the deterioration of the cytoplasm without altering the nucleus. These observations suggest that: (1) both estrogen and androgens control the viability of the granulosa cells and thereby the follicle, (2) the action of estrogen and androgen is mediated through receptors within the granulosa cells since these antihormones prevent the nuclear uptake of their respective hormone, (3) the granulosa cells of preovulatory follicles appear to be more dependent on estrogen than on androgen, and (4) each steroid appears to have a specific role in maintaining the granulosa cell; estrogens control the integrity of the nucleus while androgens preserve the cytoplasmic organization of the granulosa cell.
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    URL: http://dx.doi.org/10.1007/BF00238656
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    The morphology of the horseshoe crab (Limulus polyphemus) visual system (1981)
    Springer
    Cell & tissue research 216 (1981), S. 655-659 
    Details
    ISSN: 1432-0878
    Keywords: Eye ; Neuroeffector junction ; Octopamine ; Circadian rhythm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Efferent fibers to the compound eye of the horseshoe crab, Limulus polyphemus, not only innervate the various pigment cells, but also invade the eccentric cell dendrite and the retinula cells. This finding provides a structural basis for the coupling of circadian rhythm between the efferents and the receptor cells.
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    URL: http://dx.doi.org/10.1007/BF00238660
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    Electron-microscopic studies on reaggregate cultures of vascular smooth muscle cells from normotensive and spontaneously hypertensive rats (1981)
    Springer
    Cell & tissue research 217 (1981), S. 225-243 
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    ISSN: 1432-0878
    Keywords: Vascular smooth muscle ; Spontaneously hypertensive rat ; Reaggregate cultures ; Ultrastructure ; Collagen synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vascular smooth muscle cells were taken from the aortae of the WKY (normotensive) and SHR (spontaneously hypertensive) strains of rat by enzymatic dispersion and put into reaggregate culture. Initially the cells became individual spheroids having average diameters of 10 μm and surfaces that were either rough or smooth. The cells were far more complex than they appeared on their surfaces; after one day in culture, there was considerable internal variation in these cells. All the cells, whether WKY or SHR, lost the bulk of their cytoplasmic contents (including myofilaments, many mitochondria, and vesicular structures) in the early stages of culture and eventually became flattened. After 14 days in culture, these modified cells collected to form reaggregates that were commonly roughly spherical and several hundred μm in diameter. These reaggregates consisted of peripheral regions made up of several layers of flattened cells overlying cores formed by glia-like networks of cells similar in cytological appearance to the cells at the periphery. The meshes formed in this way contained cellular debris derived from dead cells or extrusion of cellular contents. It appears that SHR cells are quicker to form reaggregates than are WKY cells. Yet the SHR cells retained a rounded conformation after five days, whereas the WKY cells were more flattened and formed a more discrete aggregate at this stage of culture. However, by the fourteenth day of culture, differences between the two cell strains were not so pronounced, as far as could be judged by observations made with scanning and transmission electron microscopy. Both WKY and SHR cells at 14 days appeared highly secretory, possessing large Golgi systems as well as numerous ER cisternae and mitochondria. SHR cells produced greater amounts of connective tissue at all stages of culture than did WKY cells, indicating that a similar difference may contribute to the hypertension which develops naturally in situ in SHR animals.
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    URL: http://dx.doi.org/10.1007/BF00233577
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    Carbamylcholine-induced morphological changes and spatial dynamics of [Ca2+]c in Harderian glands of guinea pigs: calcium-dependent lipid secretion and contraction of myoepithelial cells (1993)
    Springer
    Cell & tissue research 274 (1993), S. 1-14 
    Details
    ISSN: 1432-0878
    Keywords: Harderian gland ; Ultrastructure ; Fura-2/AM digital imaging ; Calcium ion ; Carbamylcholine ; Myoepithelial cells ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To determine whether lipid-secreting cells have cytosolic Ca2+ concentration ([Ca2+]c)-related secretory mechanisms, morphological changes and intracellular calcium dynamics of Harderian glands of guinea pigs stimulated by secretagogs were studied by electron microspy and Fura-2/AM digital image analysis. Control glandular cells contained large lipid vacuoles that were bordered by multi-layered membranes. Rough-surfaced endoplasmic reticulum, mitochondria, and smooth-surfaced endoplasmic reticulum may be involved in lipid vacuole formation. Myoepithelial cells surrounded alveoli. After carbamylcholine (CCh, 10−6, 10−5, and 10−3 M) stimulation, lipid materials within the membranous structures were frequently discharged by an exocytotic mechanism. Conspicuous deformation of glandular cells caused by vigorous contraction of myoepithelial cells was observed in isolated alveoli after 10−6M CCh stimulation, whereas the deformaties of glandular tissues perfused via vessels were small even after 10−3M CCh stimulation. Connective tissue between glandular alveoli inhibited unbridled myoepithelial-cell contraction. Fura-2/AM digital imaging analysis revealed that CCh stimulation caused an increase in [Ca2+]c in isolated alveoli. The morphological reactions and changes in [Ca2+]c were prevented by atropine. When extracellular calcium ions were absent, enhanced extrusion of lipid vacuoles, myoepithelial-cell contraction, and a rise in [Ca2+]c after CCh stimulation were not observed. Nicotine and catecholamines had no effect on the secretion or on the dynamics of [Ca2+]c. It can be concluded that acetylcholine elicits exocytosis in glandular cells and contraction of the myoepithelial cells of Harderian glands, accompanied by an increase in [Ca2+]c. The dynamics of [Ca2+]c of the gland alveoli are mostly dependent on extracellular Ca2+.
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    Electron-microscopic immunocytochemical study of the endocrine pancreas of sea bass (Dicentrarchus labrax) (1993)
    Springer
    Cell & tissue research 274 (1993), S. 303-314 
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    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; Peptides ; Ultrastructure ; Immunogold labeling ; Sea bass ; Dicentrarchus labrax ; (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Insulin (B)-, somatostatin 25 (SST-25) (D1)-, somatostatin 14 (SST-14) (D2)-, glucagon (A)-, and glucagon PP/PYY/NPY (PP-like)-immunoreactive cells in islets of sea bass (Dicentrarchus labrax) were characterized according to their ultrastructure and immunogold labeling. Cells labeled with antisera to bonito and salmon insulin had numerous secretory granules with a small halo and round core, and a few with wide halo and round or crystalloid core. Gold particles were found throughout the granule in tissue labeled with the former but only in the core in tissue labeled with the latter. D1 cells had large granules with a medium electron-dense content and some with a darker core. D2 had smaller medium or high electron-dense secretory granules than D1 cells, located mainly in cell periphery. Glucagon-immunoreactive cells contained some granules with a polygonal core that was heavily labeled and other granules with a round core with no or hardly any labeling. Glucagon and PP-like immunoreactivity were co-localized in secretory granules, in which the gold particles showed no different distribution with the various antisera used. PYY-immunoreactive granules were also found in nerve endings. All the pancreatic endocrine cell types showing involutive characteristics are found.
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    Cutaneous and subcutaneous sensory receptors of the hagfish Myxine glutinosa with special respect to the trigeminal system (1993)
    Springer
    Cell & tissue research 274 (1993), S. 353-366 
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    ISSN: 1432-0878
    Keywords: Trigeminal nerve ; Mechanoreceptors ; Skin ; Peripheral autonomic ganglia ; Ultrastructure ; Myxine glutinosa ; Cyclostomata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The integument of the hagfish Myxine glutinosa is described with respect to the topography and the fine structural organization of the dermal and hypodermal nerve fiber plexus. Both nerve fiber plexuses contain small ganglion cells with axodendritic and axosomatic synapscs. The six barbels of the head (4 nasal and 2 oral barbels) are supplied with about 5600 afferent trigeminal nerve fibers via the right and left ophthalmic nerve. With respect to the topography of the sensory nerve terminals in the barbels different types of receptors are termed the external cuff receptor, internal cuff receptor, and perichondrial receptor. Free nerve terminals occur within the epidermal layer, especially at the tip region of the barbels and in the glassy membrane of the dermis. The hypodermal edge receptor organ extends from the ventral nasal barbel to the oral barbel. A mechanoreceptive function of the different receptor types is discussed. The innervation pattern of the barbel is similar to the innervation of the mammalian sinus hair. In this context, the barbel is a highly differentiated receptor organ able to explore the nearest surroundings with high stereognostic perception. The ganglion cells of the skin seem to represent a part of the peripheral autonomic nervous system, which is involved in the control of secretion mechanisms.
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    URL: http://dx.doi.org/10.1007/BF00318754
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    Ultrastructural study of electrophysiologically identified neurones in the paraventricular nucleus of the rat (1981)
    Springer
    Cell & tissue research 216 (1981), S. 503-512 
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    ISSN: 1432-0878
    Keywords: Paraventricular neurones ; Alcian-blue labelling ; Ultrastructure ; Electrophysiology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characterization of electrophysiologically identified neurones of the rat paraventricular hypothalamic nucleus was performed with extracellular labelling technique. The extracellularly recorded neurones are labelled with an electrophoretic deposit of alcian blue contained in the recording micropipette. The neurone thus labelled takes on a dark and shrunken appearance which enables its detection among neighbouring cells without, however, concealing its main morphological characteristics. 1) Spontaneously firing neurones, invaded by an antidromic action potential elicited by electrical stimulation of the neurohypophysis, were identified as magnocellular cells containing dense-cored vesicles of 200–250 nm in diameter. Dense-cored vesicles were not found in the antidromically activated neurones devoid of spontaneous activity. 2) Trans-synaptically activated neurones in the PVN or in its dorso-lateral edge were small cells devoid of dense secretory vesicles. 3) PV neurones in which neurohypophysial stimulation evoked no response, contained small, dense vesicles (100 nm in diameter) comparable with those found in parvocellular peptidergic neurones.
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    URL: http://dx.doi.org/10.1007/BF00238647
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    Pore canals in the cornea of a functionally specialized area of the honey bee's compound eye (1981)
    Springer
    Cell & tissue research 216 (1981), S. 491-501 
    Details
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Cornea ; Compound eye ; Honey bee (Apis mellifera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the cornea in an anatomically and functionally specialized part of the honey bee's compound eye (dorsal rim area) was examined by light microscopy, transmission electron and scanning electron microscopy. Under incident illumination the cornea appears grey and cloudy, leaving only the centers of the corneal lenses clear. This is due to numerous pore canals that penetrate the cornea from the inside, ending a few μm below the outer surface. They consist of (1) a small cylindrical cellular evagination of a pigment cell (proximal), and (2) a rugged-walled, pinetree-shaped extracellular part (distal). The functional significance of these pore canals is discussed. It is concluded that their light scattering properties cause the wide visual fields of the photoreceptor cells measured electrophysiologically in the dorsal rim area, and that this is related to the way this eye region detects polarization in skylight.
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    The sensillum capitulum, an antennal hygro- and thermoreceptive sensillum of the cockroach, Periplaneta americana L. (1981)
    Springer
    Cell & tissue research 216 (1981), S. 525-543 
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    ISSN: 1432-0878
    Keywords: Hygroreceptor ; Thermoreceptor ; Sensillum capitulum ; Cockroach ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sensillum capitulum, a hygro- and thermoreceptive sensillum of the cockroach Periplaneta americana L. is comprised of four receptor cells, one glial cell, two gland cells and four enveloping cells. Each receptor cell sends a single axon to the CNS, and has a single dendrite which extends distally. The perikarya of three receptor cells are enclosed by one of the enveloping cells (number one) and the fourth by a gland cell. The dendrites of all four receptor cells are enclosed by the same enveloping cell. The dendrites contain rootlets and many microtubules. The sensory cilia arise at the end of the dendrites at the level of the inner cavity, expand from the connecting cilium in a manner similar to those of the amphinematic scolopidia, and have numerous microtubules. The 1st enveloping cell contains scolopale rod-like structures. The sensory cilia are surrounded distally by a cuticular sheath formed within the 1st enveloping cell. One of the sensory cilia disappears distally, and the remaining ones enter the sensillum cone. Of these, one branches and the other two do not. The distal ends of the unbranched cilia are differentiated into tubular structures. The sensillum cone is comprised of an inner stem and a guard wall, neither of which is perforated. The outer cavity is enclosed by the 2nd, 3rd, and 4th enveloping cells, and distally in the antenna is closely apposed to the cuticular wall. This cavity contains lipid deposits. These structural features are discussed with regard to the mechanism of hygroreception in P. americana.
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    Stereological studies on the small intestinal epithelium of the rat (1981)
    Springer
    Cell & tissue research 217 (1981), S. 11-21 
    Details
    ISSN: 1432-0878
    Keywords: Intestinal mucosa ; Small intestinal epithelium ; Ultrastructure ; Duodenum ; Jejunum ; Stereology ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Quantitative macroscopic, light-microscopic and electron-microscopic studies were performed on the small intestine of fasted and non-fasted adult, male Sprague-Dawley rats. In non-fasted rats the small intestine was longer than in fasted rats. Due to the presence of villi the surface area in the duodenum and the jejunum was enlarged about six times. The microvilli on the villous crests caused a surface enlargement by 13 times in the duodenum (value corrected for overestimation due to section thickness), and 19 times in the jejunum of the fasted rats. At the base of the villi these values were about 50% lower. It was calculated that, in the fasted rats, the total enlargement of the luminal surface area — due to villi and microvilli — was 63 times in the duodenum and 81 times in the jejunum (corrected for section thickness). Differences between the villous crest epithelium and the villous base epithelium were also found with regard to the mean cell height, and the volume densities of the absorptive cell nuclei, the mitochondria, and the paracellular channels.
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    URL: http://dx.doi.org/10.1007/BF00233821
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    Morphology and distribution of Müller cells in the retina of the toad Bufo marinus (1993)
    Springer
    Cell & tissue research 272 (1993), S. 183-192 
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    ISSN: 1432-0878
    Keywords: Retina ; Müller cells ; Neuron-specific enolase ; Immunocytochemistry ; Quantitative analysis ; Ultrastructure ; Bufo marinus (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that an antibody against neuron-specific enolase (NSE) selectively labels Müller cells (MCs) in the anuran retina (Wilhelm et al. 1992). In the present study the light- and electron-microscopic morphology of MCs and their distribution were described in the retina of the toad, Bufo marinus, using the above antibody. The somata of MCs were located in the proximal part of the inner nuclear layer and were interconnected with each other by their processes. The MCs were uniformly distributed across the retina with an average density of 1500 cells/mm2. Processes of MCs encircled the somata of photoreceptor cells isolating them from each other by glial sheath, except for those of the double cones. Some of the photoreceptor pedicles remained free of glial sheath. Electron-microscopic observations confirmed that MC processes provide an extensive scaffolding across the neural retina. At the outer border of the ganglion cell layer these processes formed a non-continuous sheath. The MC processes traversed through the ganglion cell layer and spread beneath it between the neuronal somata and the underlying optic axons. These processes formed a continuous inner limiting membrane separating the optic fibre layer from the vitreous tissue. Neither astrocytic nor oligodendrocytic elements were found in the optic fibre layer. The significance of the uniform MC distribution and the functional implications of the observed pattern of MC scaffolding are discussed.
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    Structure of the tertiary component of the myenteric plexus in the guinea-pig small intestine (1993)
    Springer
    Cell & tissue research 272 (1993), S. 509-516 
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    ISSN: 1432-0878
    Keywords: Myenteric plexus ; Enteric nervous system ; Intestine, small ; Ultrastructure ; Innervation, of intestinal muscle ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The tertiary component of the myenteric plexus consists of interlacing fine nerve fibre bundles that run between its principal ganglia and connecting nerve strands. It was revealed by zinc iodide-osmium impregnation and substance P immunohistochemistry at the light-microscope level. The plexus was situated against the inner face of the longitudinal muscle and was present along the length of the small intestine at a density that did not vary markedly from proximal to distal. Nerve bundles did not appear to be present in the longitudinal muscle as judged by light microscopy, although numberous fibre bundles were encountered within the circular muscle layer. At the ultrastructural level, nerve fibre bundles of the tertiary plexus were found in grooves formed by the innermost layer of longitudinal smooth muscle cells. In the distal parts of the small intestine, some of these nerve fibre bundles occasionally penetrated the longitudinal muscle coat. Vesiculated profiles in nerve fibre bundles of the tertiary plexus contained variable proportions of small clear and large granular vesicles; they often approached to within 50–200 nm of the longitudinal smooth muscle cells. Fibroblast-like cells lay between strands of the tertiary plexus and the circular muscle but were never intercalated between nerve fibre varicosities and the longitudinal muscle. These anatomical relationships are consistent with the tertiary plexus being the major site of neurotransmission to the longitudinal muscle of the guinea-pig small intestine.
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    URL: http://dx.doi.org/10.1007/BF00318557
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    Sub-cellular distribution of nitrogen compounds inAzolla andAnabaena by ESI and EELS analysis (1993)
    Springer
    Protoplasma 173 (1993), S. 158-169 
    Details
    ISSN: 1615-6102
    Keywords: Azolla-Anabaena symbiosis ; Ultrastructure ; Nitrogen distribution ; Electron spectroscopic imaging ; Electron energy loss spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The sub-cellular localization of some nitrogen compounds within the leaf cavities ofAzolla filiculoides Lam. was obtained by means of electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS). The analyses were performed on ultrathin unstained sections of differentAzolla leaf cavities which contain epidermal hairs,Anabaena azollae Strasb. and bacteria. Net nitrogen distributions were visualized by image analysis, and nitrogen peaks were evidenced in spectra recorded in the same areas. Different distributions of nitrogen compounds were observed within the leaf cavities along the stem, in particular inside the epidermal hairs ofAzolla and the vegetative cells and heterocysts ofA. azollae.
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    URL: http://dx.doi.org/10.1007/BF01379004
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    Pre-fertilization ovule development inCapsella: ultrastructure and ultracytochemical localization of acid phosphatase in the meiocyte (1981)
    Springer
    Protoplasma 107 (1981), S. 27-45 
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    ISSN: 1615-6102
    Keywords: Acid phosphatase ; Capsella ; Female meiocyte ; Ovule ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pre-meiotic and prophase I ovules ofCapsella bursa-pastoris (L.) Medic.(monosporic,Polygonum type of gametophyte development) were fixed routinely or incubated in a modified Gomori medium containing β-glycerophosphate as a substrate. Prior to the beginning of meiosis the potential meiocyte is ultrastructurally similar to the other cells of the nucellus and is distinguished only by its size and position. At the initiation of prophase I dramatic ultrastructural and ultracytochemical changes take place in the female meiocyte. These include the sudden appearance of cytoplasmic structures composed of single and multiple concentric cisternae, distinctive changes in plastids and mitochondria, and the blebbing of 0.3 μm double-membraned vesicles from the nuclear envelope. The concentric cisternae encapsulate portions of cytoplasm containing ribosomes, plastids, mitochondria, ER fragments and vesicles. Both single and multiple concentric cisternae localize high levels of acid phosphatase and function as autophagic vesicles (AVs) that sequester ribosomes and organelles for destruction during meiosis. Plastids stop dividing and become more spherical during prophase I. Some plastids localize acid phosphatase and many show continuities between the outer membrane and the plastid envelope and acid phosphatase-rich RER cisternae. Mitochondria appear as dense, contracted spheres or rods. Some mitochondria localize acid phosphatase but they do not show membrane confluencies with the ER. Some of the plastids and mitochondria that are segregated into the functional megaspore at meiosis II are destroyed but others apparantly survive meiosis and give rise to the plastid and mitochondrial populations of the young gametophyte (Schulz andJensen, unpublished). The lateral and end walls of the meiocyte show patches of intense aniline blue fluorescence and the chalazal end wall of the cell is perforated with large numbers of plasmodesmata.
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    Ultrastructure of the sperms ofPlumbago zeylanica (1981)
    Springer
    Protoplasma 107 (1981), S. 85-107 
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    ISSN: 1615-6102
    Keywords: Male cytoplasmic inheritance ; Plumbago ; Pollen grain ; Pollen tube ; Sperm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Male gametes ofPlumbago zeylanica were examined in pollen grains and tubes using light and electron microscopy of chemically and physically fixed tissues, and Nomarski interference microscopy of isolated, living sperm cells. Male gametes are elongate, spindleshaped cells containing a nucleus, mitochondria, ER, ribosomes, vesicles, dictyosomes, probable microfilaments, and a variable number of plastids. In mature pollen grains ofP. zeylanica, the two sperm cells are directly linked; they share a transverse cell wall with plasmodesmata and are enclosed together by the inner vegetative cell plasma membrane. One of these two sperms is also associated with the vegetative nucleus as a consistent feature of pollen grain organization. The basis of this association appears to be a long, narrow projection of the sperm cell (averaging 〈 1 μm wide and about 30 μm long) which wraps around the periphery of the vegetative nucleus and occupies embayments of that nucleus. This association is maintained throughout pollen tube growth but becomes less extensive near the completion of tube growth and is severed following tube discharge. The consistent occurrence of the sperm-vegetative nucleus association in pollen grains, tubes and isolated pollen cytoplasm suggests that the two structures may be directly connected, but attempts to visualize this type of connection were unsuccessful. Possibly, the entwining nature and extent of complementary interfaces between vegetative nucleus and sperm may have a role in stabilizing their association. Functionally, the two sperms and vegetative nucleus appear to travel as a linked unit within the pollen tube, possibly increasing the effectiveness of gamete delivery and helping to ensure nearly simultaneous transmission of sperms into the receptive megagametophyte.
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    URL: http://dx.doi.org/10.1007/BF01275610
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    Occurrence of the suberized lamella in leaves of grasses of different photosynthetic types. I. In parenchymatous bundle sheaths and PCR (“Kranz”) sheaths (1981)
    Springer
    Protoplasma 109 (1981), S. 371-401 
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    ISSN: 1615-6102
    Keywords: C4 Photosynthesis ; C4 Types ; Leaf blades ; Poaceae ; Suberized lamella ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Leaf blades of 42 grasses (Poaceae) have been examined ultrastructurally for the occurrence of a suberized lamella in walls of parenchymatous bundle sheaths and PCR (= “Kranz”) sheaths in both large and small vascular bundles. The sample includes species from a range of major grass taxa, and represents all photosynthetic types found in the grasses. Three grasses with unusual C4 leaf anatomy were also included:Alloteropsis semialata, Aristida biglandulosa, Arundinella nepalensis. The presence of a suberized lamella in PCR cell walls was perfectly correlated with photosynthetic type. All PEP-carboxykinase type and NADP-malic enzyme type C4 species examined possessed a suberized lamella in outer tangential and radial walls, but with variable presence in inner tangential walls. PCR cells of bothAlloteropsis semialata andArundinella nepalensis also possessed a suberized lamella. A lamella was totally absent from parenchymatous bundle sheath cells of the C3 species examined (5 spp.) and ofPanicum milioides, a C3-C4 intermediate. It was also absent from PCR cells of NAD-malic enzyme type C4 species (14 spp.) andAristida biglandulosa. The results are discussed in relation to the leakage of CO2 from PCR cells, and to differences between C4 types in δ13C values, chloroplast position in PCR cells, and other anatomical characteristics.
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    Ultrastructure of cell division and reproductive differentiation of male plants in theFlorideophyceae (Rhodophyta). Mitosis inDasya baillouviana (1981)
    Springer
    Protoplasma 106 (1981), S. 329-341 
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    ISSN: 1615-6102
    Keywords: Dasya ; Mitosis ; Rhodophyta ; Spermatangia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis in the marine red algaDasya baillouviana (Ceramiales, Florideophyceae) was observed with the electron microscope. Most details of the process are quite similar to those observed in the other macroscopic red algae studied to date. However, some minor variations were noted. At late prophase a very small nuclear envelope protrusion (NEP) is formed at each division pole subjacent to the “nucleus associated organelle” known as the polar ring (PR) and 2–3 cisternae of perinuclear endoplasmic reticulum (PER) are commonly present during metaphase-anaphase. In contrast, in the other florideophycean algae where mitosis has been reported, a prominent NEP is present at late prophase (McDonald personal communication,Scott et al. 1980) and only a single cisterna of PER is observed. Additionally, during mid-late interphase and in mitotically-quiescent cells ofDasya, a single cisterna of smooth-surfaced ER is always juxtaposed with each PR. The possible significance of PER in theFlorideophyceae and other multinucleate organisms is discussed as well as the likely functions of spindle-associated smooth ER. It is suggested that ultrastructural features of mitosis should be useful as criteria to aid in the interpretation of the phylogeny of red algae.
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    Effect of cytochalasin A on actin distribution in the fission yeastSchizosaccharomyces pombe studied by fluorescent and electron microscopy (1993)
    Springer
    Protoplasma 176 (1993), S. 24-32 
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    ISSN: 1615-6102
    Keywords: Actin ; Cytoskeleton ; Schizosaccharomyces pombe ; Freeze substitution ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Actin distribution and ultrastructure of the fission yeastSchizosaccharomyces pombe treated with cytochalasin A (CA) were investigated by fluorescence microscopy using rhodamine-conjugated phalloidin (rh-ph) and freeze substitution electron microscopy. Among the cytochalasins tested, CA was most effective and at 5 μg/ ml inhibited the appearance of the actin ring at the cell equator at the stage prior to septum formation and the accumulation of actin dots at the septum-forming site both in wild-type cells and the mutantcdc 11, which is defective in septum formation at restrictive temperature. Freeze substitution electron microscopy of CA-treated cells revealed the displacement and morphological alteration of cytoplasmic vesicles and dictyosomes within 30 min and the appearance of dense bodies in the cytoplasm. A sub-population of cytoplasmic vesicles and dictyosomes were insensitive to CA and maintained their original structure. An electron less dense layer containing filamentous material was noted beneath the plasma membrane and thought to be the area of heavy actin patches stained with rh-ph at the cells ends. These results suggest that CA disrupted an actin network that normally maintains the organization of the secretory pathway involving dictyosomes and vesicles.
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    URL: http://dx.doi.org/10.1007/BF01378936
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    Membrane coatings on the generative cell surface of freeze-substituted monocotyledon pollen (1993)
    Springer
    Protoplasma 176 (1993), S. 84-88 
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    ISSN: 1615-6102
    Keywords: Pollen (high-pressure freezing) ; Freeze-substitution ; Generative cell ; Plasma membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary High-pressure freezing/freeze-substitution/TEM were employed for studying plasma membrane coatings in mature pollen grains. Data are presented on 6 species belonging to 4 not closely related orders. Two sorts of coatings were observed at the cytoplasmic face of the vegetative plasma membrane bordering the generative cell: (i) A dense, uniform layer with an average thickness of 10 nm (“fluffy coating”). (ii) “Strip-shaped projections” protruding rectangularly into the vegetative cytoplasm. They are 25 to 35 nm in height and set at a constant distance of about 30 nm from each other. Their maximum length, estimated from grazing sections, is about 400 nm. This is the first description of periodically arranged plasma membrane protrusions in freeze-substituted plant cells. Both kinds of membrane coatings are species-and age-dependent features. Especially “strip-shaped projections” are frequently intimately associated with polymorphic endoplasmic reticulum surrounding the generative cell, a hitherto unreported pattern. It is presumed that “strip-shaped projections” are similar to, or even identical with, “ordered ridges” observed in freeze-fracturedPhoenix dactylifera pollen.
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    URL: http://dx.doi.org/10.1007/BF01378942
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    The generative cell and its close association with the endoplasmic reticulum of the vegetative cell in pollen ofCyrtandra pendula (Gesneriaceae) (1993)
    Springer
    Protoplasma 177 (1993), S. 73-81 
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    ISSN: 1615-6102
    Keywords: Cyrtandra pendula ; Generative cell ; Endoplasmic reticulum ; Pollen grain ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the generative cell (GC) was examined in the bicellular pollen ofCyrtandra pendula. The essential stages are: (1) GC attached to the inline, (2) GC detached and spheroidal in shape, (3) GC mature and elongated. Cisternae of the endoplasmic reticulum (ER) of the vegetative cell are in close contact with the GC at all stages of development. In stages (1) and (2) the entire, slightly undulated surface of the GC is surrounded by tightly appressed, single ER tubules or short stacks. In mature pollen grains (stage 3) the shape of the GC as well as the arrangement of the surrounding ER changes conspicuously. The GC is now spindleshaped and its surface is wrinkled. An ER tubule is present in each invagination. These ER tubules form a cage-like framework around the GC. In the cytoplasm of the generative cell, 6 to 7 microtubular bundles with longitudinal orientation can be observed. They seem to be responsible for maintaining the elongate shape of the GC. During all stages of development vegetative ER cisternae are the only elements intimately associated with the GC wall. This feature indicates that the ER may contribute to the formation of the undulated outer shape of the GC. Also discussed is the possibility that energy-carrying substances are conveyed into the GC through the channels of ER.
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    Microspore development inBrassica napus and the effect of high temperature on division in vivo and in vitro (1993)
    Springer
    Protoplasma 172 (1993), S. 154-165 
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    ISSN: 1615-6102
    Keywords: Brassica napus ; Cell division ; High temperature ; Microspore ; Embryogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Brassica napus cv. Topas microspores isolated and cultured near the first pollen mitosis and subjected to a heat treatment develop into haploid embryos at a frequency of about 20%. In order to obtain a greater understanding of the induction process and embryogenesis, transmission electron microscopy was used to study the development of pollen from the mid-uninucleate to the bicellular microspore stage. The effect of 24 h of high temperature (32.5 °C) on microspore development was examined by heat treating microspore cultures or entire plants. Mid-uninucleate microspores contained small vacuoles. Late-uninucleate vacuolate microspores contained a large vacuole. The large vacuole of the vacuolate stage was fragmented into numerous small vacuoles in the late-uninucleate stage. The late-uninucleate stage contained an increased number of ribosomes, a pollen coat covering the exine and a laterally positioned nucleus. Prior to the first pollen mitosis the nucleus of the lateuninucleate microspore appeared to be appressed to the plasma membrane; numerous perinuclear microtubules were observed. Microspores developing into pollen divided asymmetrically to form a large vegetative cell with amyloplasts and a small generative cell without plastids. The cells were separated by a lens-shaped cell wall which later diminished. At the late-bicellular stage the generative cell was observed within the vegetative cell. Starch and lipid reserves were present in the vegetative cell and the rough endoplasmic reticulum and Golgi were abundant. The microspore isolation procedure removed the pollen coat, but did not redistribute or alter the morphology of the organelles. Microspores cultured at 25 °C for 24 h resembled late-bicellular microspores except more starch and a thicker intine were present. A more equal division of microspores occurred during the 24 h heat treatment (32.5 °C) of the entire plant or of cultures. A planar wall separated the cells of the bicellular microspores. Both daughter cells contained plastids and the nuclei were of similar size. Cultured embryogenie microspores contained electron-dense deposits at the plasma membrane/cell wall interface, vesicle-like structures in the cell walls and organelle-free regions in the cytoplasm. The results are related to embryogenesis and a possible mechanism of induction is discussed.
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    Early events in division of the generative cell ofOrnithogalum virens (1993)
    Springer
    Protoplasma 172 (1993), S. 77-83 
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    ISSN: 1615-6102
    Keywords: Ornithogalum virens ; Generative cell ; Mitosis ; Pollen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ornithogalum virens is a bicellular pollen species. In mature pollen, the generative nucleus is at advanced prophase. Mitosis of the generative cell is resumed just after pollen rehydration and prometaphase occurs within 10 min of germination. Prometaphase is manifested by nuclear envelope breakdown and the appearance of spindle microtubules in the nucleoplasm region. At this stage the number of cytoplasmic microtubules located in the generative cell periphery appears to decrease. Endoplasmic reticulum-like cisternae originating from the nuclear envelope tend to be spaced around the chromosomes, outside the area of the forming mitotic spindle. Some also begin to penetrate the spindle area. The results are discussed in terms of the generative cell cycle in bicellular pollen.
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    Ultrastructure of transfer cells in spontaneous nodules of alfalfa (Medicago sativa) (1993)
    Springer
    Protoplasma 172 (1993), S. 64-76 
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    ISSN: 1615-6102
    Keywords: Alfalfa ; Spontaneous nodules ; Development ; Rhizobium meliloti ; Transfer cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spontaneous nodules were formed on the primary roots of alfalfa plants in the absence ofRhizobium. Histologically, these white single-to-multilobed structures showed nodule meristems, cortex, endodermis, central zone, and vascular strands. Nodules were devoid of bacteria and infection threads. Instead, the larger cells were completely filled with many starch grains while smaller cells had very few or none. Xylem parenchyma and phloem companion cells exhibited long, filiform and branched wall ingrowths. The characteristic features of both types of transfer cells were polarity of wall ingrowths, high cytoplasmic density, numerous mitochondria, abundant ribosomes, well-developed nucleus and nucleolus, and vesicles originated from rough endoplasmic reticulum. These results were compared with normal nodules induced byRhizobium. Our results suggest that xylem parenchyma and phloem companion transfer cells are active and probably involved in the short distance transport of solutes in and out of spontaneous nodules. Since younger nodules showed short, papillate, and unbranched wall ingrowths, and older tissue showed elongated, filiform and branched wall ingrowths, the development of wall ingrowths seemed to be gradual rather then abrupt. The occurrence of both type-A and -B wall ingrowths suggests that phloem companion transfer cells may be active in loading and unloading of sieve elements. Since there were no symbiotic bacteria and thus no fixed nitrogen, it is tempting to speculate that xylem parenchyma transfer cells may be re-transporting accumulated carbon from starch grains to the rest of the plant body by loading xylem vessels. Fusion of ER-originated vesicles with wall ingrowth membrane indicated the involvement of ER in the membrane formation for elongating wall ingrowths. Since transfer cells were a characteristic feature of both spontaneous andRhizobium-induced nodules, their occurrence and development is controlled by the genetic make-up of alfalfa plant and not by a physiological source or sink emanating from symbiotic bacteria.
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    The effects of abscisic acid on the maturation ofBrassica napus somatic embryos (1993)
    Springer
    Protoplasma 174 (1993), S. 147-157 
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    ISSN: 1615-6102
    Keywords: Abscisic acid ; Brassica napus ; Embryo maturation ; Reserves metabolism ; Somatic embryos ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A comparison of embryos, cultured for increasing periods of time with and without abscisic acid (ABA), was undertaken to investigate, at the ultrastructural level, the influence of this growth regulator on the maturation of rapeseed (Brassica napus) somatic embryos. In the absence of ABA, the embryos germinated precociously while lipid bodies (LB), which were not numerous, soon degraded, as revealed by a depletion process associated with the appearance of morphologically mature glyoxysomes and an increase in the number of mitochondria. Moreover, a lack of protein bodies indicated that storage protein accumulation was not initiated under these conditions. On the contrary, the addition of ABA (10 μM) induced marked modification of embryo metabolism. Indeed, ABA completely prevented precocious embryo germination and inhibited lipid reserve catabolism. Moreover, the formation of small vacuoles and proliferation of rough endoplasmic reticulum in their vicinity suggested the onset of storage protein accumulation. After 15 days in the presence of ABA, the embryos contained abundant lipid and protein bodies. Nevertheless, these somatic embryos were not exactly the same as their mature zygotic counterparts since differences were found in chloroplasts, amyloplasts, and nuclear structures. These observations suggest that additional factors might be required to obtain fully mature somatic embryos.
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    Etude ultrastructurale de la spermatogènese chezTrichinella spiralis Owen 1835 (Nématode trichuroïde) (1981)
    Springer
    Parasitology research 64 (1981), S. 207-215 
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    ISSN: 1432-1955
    Keywords: Ultrastructure ; Spermatogenesis ; Nematoda ; Trichinella spiralis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'étude ultrastructurale de la spermatogénèse chezT. spiralis a permis de retrouver chez cette espèce les caractères morphologiques observés dans la lignée mâle chez la plupart des Nématodes, c'est-à-dire absence de flagelle chez le spermatozoïde, absence de reconstitution de l'enveloppe nucléaire après divisions méiotiques, structure atypique du centriole. Elle a permis de situer le spermatozoïde par rapport aux classifications antérieurement proposées.
    Notes: Abstract The ultrastructural study of spermatogenesis inT. spiralis demonstrated the main characteristics of the male germ cells in the class Nematoda, i.e. lack of flagella, lack of reconstitution of the nuclear envelope after the meiotic divisions, and atypical structure of the centriole. The spermatozoon ofT. spiralis was compared with previous classifications of the Nematoda spermatozoa.
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    URL: http://dx.doi.org/10.1007/BF00930498
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    The ultrastructure of the epidermis of the redia ofParorchis acanthus nicoll (Digenea; Philophthalmidae) (1981)
    Springer
    Parasitology research 65 (1981), S. 19-30 
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    ISSN: 1432-1955
    Keywords: Parorchis acanthus ; Redia ; Ultrastructure ; Epidermis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Regional and age differences in the epidermis of the redia ofP. acanthus have been studied by transmission electron microscopy. The depth of the outer cytoplasmic epidermis increases by four times from stage I to stage III and the microvilli double their length and branch by stage II. Electron-dense and electron-lucent membrane bound bodies are present in all stages, the latter being released onto the surface as vesicles. Multivesicular bodies appear in stage III. All are formed in one type of secretory epidermal cell body. Anterior and posterior concentric folds, of thickened outer cytoplasmic epidermis only, increase the surface area and also the diameter of the redia on contraction. In stages I and II the apical regions of the ventro-lateral processes and birth papilla, and the lattice pattern on the posterior papilla, each consisting of thickened outer cytoplasmic epidermis only, may provide rigidity and support during migration. The uniciliate sensory receptors appear to be mechanoreceptors.
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    URL: http://dx.doi.org/10.1007/BF00926550
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    The glomerulus of a stenohaline fresh-water teleost, Carassius auratus gibelio, adapted to saline water (1981)
    Springer
    Cell & tissue research 220 (1981), S. 73-85 
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    ISSN: 1432-0878
    Keywords: Glomerulus ; Stenohaline fresh-water teleost ; Salt-water adaptation ; Kidney ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Prussian carp, Carassius auratus gibelio, were maintained in aquaria with a salinity of 15‰ for 3 months. More than 90% of the glomeruli disappeared from the tissue as a result of the adaptation to saline water. Kidney tissue was excised and prepared for electron microscopy after perfusion fixation in situ. The fine structure of the renal corpuscle was compared with the normal ultrastructure of glomeruli of control fish from fresh-water aquaria. The main alterations include retraction of the endothelium from the basement membrane, widening of the subendothelial region, folding of the thickened basement membrane and epithelial layer, and the dislocation of slit diaphragms. The findings are discussed in relation to developmental stages of mammalian glomeruli and glomeruli from tissue cultures. The structural changes of the rudimentary glomeruli of the carp kept in 15‰ salt water differ from those observed in euryhaline fish from sea water.
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    URL: http://dx.doi.org/10.1007/BF00209967
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    Developmental stages and localization of peroxidatic activity in the leucocytes of three teleost species (Cyprinus carpio L.; Tinca tinca L.; Salmo gairdneri Richardson) (1981)
    Springer
    Cell & tissue research 220 (1981), S. 163-180 
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    ISSN: 1432-0878
    Keywords: Leucocytes ; PO-reactivity ; Teleosts (Cyprinus carpio L., Tincatinca L., Salmo gairdneri R.) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural localization of peroxidase (PO) in the leucocytes of three teleosts (Cyprinus carpio L., Tinca tinca L., Salmo gairdneri R.) has been investigated using the 3,3′-diaminobenzidine method. In the heterophilic granulocytes the granules show a species specific structure and are PO-positive at pH 7.6. They can be traced back to small granules arising near the Golgi apparatus (GA) in the promyelocyte. They coalesce to form larger granules and gradually change into the mature type. Myelocytes contain small unreactive granules, and these represent a second granule population. Eosinophils contain one PO-positive granule type (at pH 9), and these granules show a varying density during cell maturation. Basophils are present only in the Cyprinid species, and contain unreactive granules originating from precursors displaying a weakly positive reaction at pH 7.6. The active secretory organelles (RER, GA) are PO-negative, except for a weakly positive reaction in the flocculent matrix of the inner G-cisternae. In promonocytes and monocytes the granules are unreactive, but in the macrophages PO-positive staining occurs in a few small to medium sized granules, and in large vacuoles. At least some of these latter are apparently derived from phagolysosomes containing digested erythrocytes. Thrombocytes and lymphocytes are unreactive. The successive development of PO-positive and negative granule populations in the heterophils, and the PO-reactivity of eosinophils and basophils, show some similarities to the corresponding cells in higher vertebrates, but an analogous PO-positive (“azurophil”) granule type in monocytes seems to be absent.
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    Ultrastructural studies on the nucleoli of the follicle cells in the Lizards Acanthodactylus scutellatus hardyi and Eremias brevirostris (1981)
    Springer
    Cell & tissue research 214 (1981), S. 169-180 
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    ISSN: 1432-0878
    Keywords: Nucleolus ; Pyriform cells ; Intermediate cells ; Lizards ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the nuclei in the ovarian follicular cells has been examined in the lizards Acanthodacylus scutellatus hardyi, and Eremias brevirostris. During certain growth stages, the nuclei of the intermediate and the pyriform cells become large and conspicuous, and usually contain numerous morphologically variable nucleoli. The latter may be nucleolonemal, compact, ring-shaped, “filamentous”, “fine-filamentous”, “amorphous” or “course-granular” in type, and the number and type in each nucleus seems to be related to the developmental stage. The type of nucleolus may indicate different phases of activity in the nucleus and may also suggest an association with the production of different types of RNA.
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    URL: http://dx.doi.org/10.1007/BF00235154
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    Identification and morphometric evaluation of the synapses of optic nerve afferents in the optic tectum of the axolotl (Ambystoma mexicanum) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 593-611 
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    ISSN: 1432-0878
    Keywords: Synapses ; Optic afferents ; Optic tectum ; Axolotl ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The terminals of retinal afferents in the tectum of the axolotl have been identified ultrastructurally using techniques of horseradish peroxidase-filling and degeneration. The mitochondria in filled structures show a characteristic electron-lucent matrix. After both eyes have been removed, terminals with light mitochondria disappear from the area known to receive an optic input. In this area the presence of light mitochondria is almost always diagnostic of the retinal origin of a bouton. The synapses are similar to those assumed to be of retinal origin in other vertebrates. Detailed morphometric analysis has been carried out on identified optic synapses in the optic tectum of the axolotl.
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    The ultrastructure of the innervation of the intestinal wall in the teleosts Myoxocephalus scorpius and Pleuronectes platessa (1981)
    Springer
    Cell & tissue research 214 (1981), S. 651-658 
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    ISSN: 1432-0878
    Keywords: Intestine ; Teleost ; Ultrastructure ; Innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the intestinal wall in the teleosts Myoxocephalus and Pleuronectes was examined electron microscopically. Two classes of axons can be identified. The first, which is in the majority, contains numerous 50–150 nm granular vesicles as well as some 40–50 nm agranular vesicles while the second contains predominantly the 40–50 nm agranular vesicles. Chromate/dichromate staining methods suggest that the first type is aminergic. Both types lie in close association with the perikarya of intrinsic myenteric neurons but only axons containing predominantly agranular vesicles have synaptic membrane specialisations. No axon bundles pass into the longitudinal muscle layer in Myoxocephalus gut and though some do in Pleuronectes, they do not closely approach the smooth muscle cells. Axons containing large granular vesicles lie in intimate contact with the myocytes of the circular muscle layer. Both axon types pass through the submucosa to form a plexus underneath the mucosal epithelium. Varicosities containing agranular or granular vesicles are separated from the epithelial cells by a gap of about 200 nm in which lies a basal lamina.
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    Nerves containing substance P, vasoactive intestinal polypeptide, enkephalin or somatostatin in the guinea-pig taenia coli (1981)
    Springer
    Cell & tissue research 215 (1981), S. 21-39 
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    ISSN: 1432-0878
    Keywords: Peptidergic nerves ; Guinea-pig taenia coli ; Substance P ; Vasoactive intestinal peptide ; Somatostatin ; Enkephalin ; Ultrastructure ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The guinea-pig taenia coli is rich in peptide-containing nerves. Nerve fibres containing substance P (SP), vasoactive intestinal peptide (VIP), or enkephalin, were numerous in the smooth muscle while somatostatin fibres were very few. Nerve fibres displaying SP or VIP immunoreactivity were numerous in the myenteric plexus. Enkephalin nerve fibres were fairly numerous in the plexus while somatostatin nerve fibres were sparse. Nerve cell bodies containing immunoreactive SP or VIP were regularly seen in the plexus. Delicate varicose elements of the different types of nerve fibres were found to ramify around nerve cell bodies in a manner suggestive of innervation. In the electron microscope the various peptide-storing nerve fibres (i.e., elements containing SP, VIP or enkephalin) were found to contain a varying number of fairly large, electron-opaque vesicles in the varicose swellings. These vesicles represent the storage site of the neuropeptides. The isolated taenia coli responded to electrical nerve stimulation with a contraction. After cholinergic and adrenergic blockade the contractile response was replaced by a relaxation followed by a contraction upon cessation of stimulation. SP contracted the taenia while VIP caused a relaxation. The enkephalins raised the resting tension slightly while somatostatin had no effect. These observations are compatible with a role for SP as an excitatory neurotransmitter and for VIP as an inhibitory one, and with the view that both SP neurones and VIP neurones act as motor neurones. In preparations contracted by SP the electrically induced contractions were reduced in amplitude while the electrically induced relaxations seen after adrenergic and cholinergic blockade were enhanced in amplitude. In preparations relaxed by VIP there was an increased contractile response to electrical stimulation, while in the atropine + guanethidine-treated preparation the electrically induce relaxations were reduced in amplitude. The enkephalins reduced the contractile response to electrical stimulation, while somatostatin induced a very small reduction in the amplitude of such responses. These observations suggest that SP neurones and VIP neurones may play additional roles as interneurones. Somatostatin neurones probably act as interneurones. Enkephalin-containing fibres may serve to modify the release of transmitter from other nerves in the smooth muscle, perhaps through axo-axonal arrangements. Alternatively, the enkephalin nerve fibres in the smooth muscle are afferent elements involved in mediating sensory impulses to the myenteric plexus.
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    URL: http://dx.doi.org/10.1007/BF00236246
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    Hepatocyte differentiation during early fetal development in the rat (1981)
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    Cell & tissue research 215 (1981), S. 133-142 
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    ISSN: 1432-0878
    Keywords: Rat fetus ; Hepatocyte differentiation ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat hepatocyte differentiation between day 12 and 19 of fetal life was studied by electron microscopy. The cytoplasmic structures involved in synthetic and secretory function, i.e., rough endoplasmic reticulum and Golgi apparatus, appear to be the first to differentiate, and their development is probably related to the secretion of different kinds of plasma proteins. The cytoplasmic organelles involved in other hepatic functions develop later: lysosomes from day 15, peroxysomes, glycogen rosettes and smooth endoplasmic reticulum still later. However, the morphological differentiation of bile canaliculi begins from day 12.
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    The hypothalamic magnocellular system in the domestic fowl (1981)
    Springer
    Cell & tissue research 215 (1981), S. 113-131 
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    ISSN: 1432-0878
    Keywords: Hypothalamus ; Neurosecretory cells ; Domestic fowl ; Golgi study ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the rostral hypothalamus of the domestic fowl, the magnocellular neurosecretory nuclei show a peculiar differentiation. Golgi studies of the supraoptic and paraventricular nuclei of the fowl reveal at least two major cell types: 1) large multipolar neurons, and 2) small interneurons. Golgi impregnations provide a detailed cytoarchitectural picture of the large-sized cells; the latter may well correspond to the neurosecretory cells demonstrated in the same regions by selective staining, and immunocytochemical and electron microscopical techniques. Electron microscopically, neuronal perikarya are observed to contain variable amounts of neurosecretory granules (100–200 nm in diameter; mean diameter of 160 nm) scattered throughout the cytoplasm. The diameters of these granules do not differ statistically in the two principal nuclear areas examined. The perikarya of these neurons display only a few axosomatic synapses containing electron-lucent and dense-cored vesicles (70–90 nm in diameter). Numerous nerve terminals of this type also end on the dendritic ramifications in the surrounding neuropil.
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    Input and output synapses on identified motor neurones of a locust revealed by the intracellular injection of horseradish peroxidase (1981)
    Springer
    Cell & tissue research 215 (1981), S. 325-332 
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    ISSN: 1432-0878
    Keywords: Horseradish peroxidase ; Locust ; Motor neurone ; Synapse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Physiologically characterised motor neurones in the thoracic ganglia of the locust were injected with horseradish peroxidase in order that the spatial relationship between their input and output synapses could be observed with the electron microscope. A modification in the development procedure for the peroxidase ensured that the internal fine structure of the stained neurones was not obscured by the diaminobenzidine reaction product. Input and output synapses may occur within 1 μm of each other on the neuropilar processes of the motor neurones. This supports physiological evidence that motor neurones may be involved in local circuit interactions within the thoracic ganglia.
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    URL: http://dx.doi.org/10.1007/BF00239118
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    Differentiation and transdifferentiation of adrenal chromaffin cells of the guinea-pig (1981)
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    Cell & tissue research 215 (1981), S. 341-367 
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    ISSN: 1432-0878
    Keywords: Adrenal chromaffin cells ; Plasticity ; Eye chamber transplants ; Ultrastructure ; Catecholamine biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Autografts of adrenal chromaffin cells from adult guinea pigs to the anterior chamber of the eye were studied electron microscopically and both histo-and biochemically 4, 8 and 12 weeks after transplantation. Transplanted chromaffin cells resembled in many respects their in-situcounterparts: they stored varying amounts of granular vesicles, which were reduced in diameter, but displayed mostly cores of low or medium electron densities suggesting predominant storage of a secondary amine. Concomitant biochemical determinations of catecholamines (CA) and phenylethanolamine N-methyltransferase (PNMT) activity revealed a distinct reduction of total CA and PNMT activity, but no change in the proportion of adrenaline (A) to noradrenaline (NA) after 4 weeks. However, an increase of NA and almost equal amounts of A and NA were found after 8 weeks. CA-histofluorescence and electron microscopy revealed that axon-like processes with varicosities extend from chromaffin cells and contain the large “chromaffin” vesicles (100–200 nm in diameter) in addition to small clear and dense-cored vesicles (40–80 nm in diameter). Processes of chromaffin cells grew in all directions over the host iris and were also found in close proximity to smooth muscle cells the sympathetic nerve supply of which had been cut by removing the superior cervical ganglion. Administration of 5-and 6-hydroxydopamine (OHDA) resulted in characteristic labeling and ultramorphological changes in axons, but caused alterations in chromaffin cell bodies only 8 weeks after transplantation. Transplanted chromaffin cells became reinnervated by nerve fibres that are considered to be cholinergic fibres derived from the ciliary ganglion. Transplanted chromaffin cells also exhibited synapse-like contacts with each other. The present study shows that chromaffin cells from adult guinea pigs transplanted to the anterior chamber of the eye retain a large number of differentiated properties. Formation of axon-like processes by these cells indicates that the anterior chamber of the eye favours transdifferentiation, as does tissue culture (Unsicker et al. 1978a), eliciting a cell type that displays features of both a sympathetic neurone and a SIF-cell.
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    Effect of disulfiram on the ultrastructure of the peptidergic and aminergic cells in the pars intercerebralis of Galleria mellonella (Lepidoptera) (1981)
    Springer
    Cell & tissue research 215 (1981), S. 417-424 
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    ISSN: 1432-0878
    Keywords: Galleria ; Neurosecretory cells ; Pars intercerebralis ; Disulfiram ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Injection of disulfiram, a specific inhibitor of noradrenaline synthesis, evokes changes in two different types of neurons in the brain of Galleria mellonella: neurones containing dense-core vesicles (60–80 nm) and peptidergic cells containing 180–200 nm neurosecretory granules. The lowering of the electron density of the dense-core vesicles of 60–80 nm seems to be directly connected with disulfiram administration, while the decrease of the amount of neurosecretory material in the neurosecretory cells of type I seems to be a secondary effect of the drug injection. The participation of noradrenaline in the regulation of the secretory activity of type I peptidergic neurosecretory cells of the pars intercerebralis is postulated.
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    Ultrastructural studies on oogenesis in symphyla (1981)
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    Cell & tissue research 215 (1981), S. 431-436 
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    ISSN: 1432-0878
    Keywords: Oogenesis ; Cortical granules ; Chorion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the oocytes of Hanseniella nivea, cortical granules are formed in the peripheral ooplasm during late stages of oogenesis. Single Golgi elements are involved in the process. Concurrent with the formation of cortical granules is the appearance of a chorion on the oocyte surface. Precursors of this envelope are most likely synthesized by follicle cells.
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    Effects of pimozide on the ultrastructure of the pars intermedia in the rat (1981)
    Springer
    Cell & tissue research 217 (1981), S. 397-403 
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    ISSN: 1432-0878
    Keywords: Pituitary gland ; Rat ; MSH-cells ; Pimozide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of pimozide, a dopamine receptor-blocking agent, were studied in the pars intermedia of the rat. The animals received 100 μg/100 g pimozide daily for 2, 5, 10, 15, and 20 days. Pimozide induces ultrastructural changes after 5 days of treatment. About 50% of the MSH-cells display characteristics of stimulation. Their cytoplasm is partially or totally depleted of secretory granules. The rough endoplasmic reticulum displays a network of interconnecting cisternae and ribbon-like structures. The well-developed Golgi complexes exhibit numerous dilatations of their cisternae, which contain electron-dense material. The nerve endings are not altered. Twenty days after treatment, the above-described changes have not decreased in magnitude. The present findings suggest that pimozide stimulates the mechanism of synthesis and release in some MSH-cells, most probably the elements underlying an inhibitory dopaminergic control.
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    Ultrastructure of spermiogenesis in Liza aurata Risso, 1810 (Teleostei, Mugilidae) (1981)
    Springer
    Cell & tissue research 217 (1981), S. 415-424 
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    ISSN: 1432-0878
    Keywords: Secondary spermatocytes ; Spermatids ; Spermatozoa ; Marine teleost ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sequential cytological events in late spermatogenesis of Liza aurata were studied from the stage secondary spermatocytes to that of mature spermatozoa. Spermiogenesis involves preparatory morphological events followed by conspicuous modifications such as intracellular movements (diplosome and mitochondrion migration, spermatid lengthening, nuclear rotation) and structural changes (dense chromatin granules, increase in size of mitochondria, loss of cytoplasm). Mature spermatozoa, with a round nucleus and a pseudo-midpiece are of a primitive type, even compared with spermatozoa of other teleosts.
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    Ultrastructural study of the postembryonic development of the neural lamella of Galleria mellonella L. (Lepidoptera) (1981)
    Springer
    Cell & tissue research 217 (1981), S. 425-433 
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    ISSN: 1432-0878
    Keywords: Lepidoptera ; Neural lamella ; Postembryonic development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neural lamella encapsulating the brain of the wax moth Galleria mellonella develops from a very thin (80–120 nm) layer in the first larval instar, resembling the basal lamina, to a thick (1–4 μm) sheath composed of two zones in the seventh (last) instar. After its breakdown at the time of larval-pupal ecdysis the neural lamella is reconstructed in the pupa, 2–3 days before pupaladult ecdysis. The cells of the perineurium seem to be responsible for the formation of the neural lamella, both in the larva and pupa, even though its ultrastructure differs at these stages.
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    Isolation and primary culture of adult human hepatocytes (1981)
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    Cell & tissue research 218 (1981), S. 13-21 
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    ISSN: 1432-0878
    Keywords: Human ; Isolated hepatocytes ; Primary culture ; Albumin synthesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Biopsy tissue of adult human liver was gently dissociated with collagenase followed by Dispase. By repeated low g centrifugation, a large number of almost pure, viable hepatocytes was obtained. This is the first report of a successful procedure for obtaining adult human hepatocytes for study in tissue culture. The isolated cells have the typical morphology of liver parenchyma, and these characteristics persist throughout the period of culturing. Evidence of their function is indicated by albumin synthesis. This procedure is now being used to study human hepatocyte functions in vitro and the effects of a variety of agents including carcinogens and viruses.
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    Ultrastructure of the rat thymus: The micro-environment of T-lymphocyte maturation (1981)
    Springer
    Cell & tissue research 218 (1981), S. 279-292 
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    ISSN: 1432-0878
    Keywords: Thymus micro-environment (rat) ; Epithelial cells ; Macrophages ; Interdigitating cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the micro-environment of the fully functional rat thymus was studied. The thymus consists of two discrete compartments, viz., an epithelial and a mesenchymal compartment. Thymus fibroblasts/fibrocytes, mast cells and granulocytes, are restricted to the mesenchymal compartment. The thymocyte maturation process seems to occur in the epithelial compartment in a network of reticular epithelial cells. The cortex is finely meshed and filled with proliferating thymocytes and some scattered macrophages. Moreover, in the medulla vacuolated epithelial cells form part of a loosely meshed reticulum which is filled with thymocytes and interdigitating cells (IDCs). IDCs frequently contain Birbeck granules and appear to be phagocytic. Together with macrophages, they probably enter the thymus, predominantly in the cortico-medullary region, and cross the separating wall between the two compartments. Some functional aspects of the non-lymphoid cells and in particular the IDCs, which form the micro-environment of the thymus, are discussed with respect to T-cell development.
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    Glycoprotein gonadotropin in the plasma and its cellular origin in the adenohypophysis of sham-operated and ovariectomized rainbow trout, salmo gairdneri (1981)
    Springer
    Cell & tissue research 218 (1981), S. 439-448 
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    ISSN: 1432-0878
    Keywords: Pituitary salmonids ; GTH-cells ; Ultrastructure ; Ovariectomy ; Radioimmunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Among the cells of the pituitary generally believed to produce glycoprotein gonadotropin (GTH) five forms were distinguished, based on the amount and the diameter of granules and globules and the appearance of the rough endoplasmic reticulum. In sham-operated trout so-called “globular” cells predominated, whereas after ovariectomy these were replaced by so-called “cisternal” cells, suggesting that both belong to one GTH-cell type. In addition, ovariectomy caused a strong increase in plasma GTH-levels. This indicates that the transition from globular to cisternal cells is accompanied by extrusion of GTH, and thus points to a storage of GTH in the granules and globules. It is argued that one of the five forms has the morphological characteristics of thyrotropic cells and may not produce glycoprotein GTH.
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    Ultrastructure of muscle fibres in head and axial muscles of the perch (Perca fluviatilis L.) (1981)
    Springer
    Cell & tissue research 219 (1981), S. 111-131 
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    ISSN: 1432-0878
    Keywords: Fish ; muscle fibre types ; Ultrastructure ; Morphometry ; Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary White, pink, red and deep red fibres, selected from a head muscle and from axial muscles of the perch, show significant differences in actin filament length, Z line thickness, Z line lattice space, myofibril girth, the percentages volume occupied by T system and terminal cisternae of the SR, and in the degree of T system SR contact per sarcomere. In both muscles the degree of T system SR contact decreases in the order: white, pink, red, deep red, which suggests a decrease of contraction velocity in the same order. The position of the T system (at the Z line or at the AI junction) is related to the actin filament length. The actin filaments in the red fibres are appreciably longer than in the white, which suggests that the sarcomeres of the red fibres have a broader length-tension curve. The Z line thickness is positively correlated with the actin filament length and, in the white and the red fibres, negatively with the degree of sarcomere shortening. Thicker Z lines are suggested to allow greater sarcomere sizes (length or girth). The percentage volume occupied by mitochondria varies independently of the extent of membrane systems. The ultrastructural characteristics of the fibre types are in agreement with the functional roles as reported in literature.
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    URL: http://dx.doi.org/10.1007/BF00210022
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    Ultrastructure of the pineal organ of the killifish, Fundulus heteroclitus, with special reference to the secretory function (1981)
    Springer
    Cell & tissue research 219 (1981), S. 355-369 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Secretory function ; Photosensory function ; Ultrastructure ; Killifish, Fundulus heteroclitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal organ of the killifish, Fundulus heteroclitus, was investigated by electron microscopy under experimental conditions; its general and characteristic features are discussed with respect to the photosensory and secretory function. The strongly convoluted pineal epithelium is usually composed of photoreceptor, ganglion and supporting cells. In addition to the well-differentiated photosensory apparatus, the photoreceptor cell contains presumably immature dense-cored vesicles (140–220 nm in diameter) associated with a well-developed granular endoplasmic reticulum in the perinuclear region and the basal process. These dense-cored vesicles appear rather prominent in fish subjected to darkness. The ganglion cell shows the typical features of a nerve cell; granular endoplasmic reticulum, polysomes, mitochondria and Golgi apparatus are scattered in the electron-lucent cytoplasm around the spherical or oval nucleus. The dendrites of these cells divide into smaller branches and form many sensory synapses with the photoreceptor basal processes. Lipid droplets appear exclusively in the supporting cell, which also contains well-developed granular endoplasmic reticulum and Golgi apparatus. Cytoplasmic protrusions filled with compact dense-cored vesicles (90–220 nm in diameter) are found in dark-adapted fish. The origin of these cytoplasmic protrusions, however, remains unresolved. Thus, the pineal organ of the killifish contains two types of dense-cored vesicles which appear predominantly in darkness. The ultrastructural results suggest that the pineal organ of fish functions not only as a photoreceptor but also as a secretory organ.
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    URL: http://dx.doi.org/10.1007/BF00210154
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    The fine structure of the neural lobe of the mouse after transplantation under the kidney capsule (1981)
    Springer
    Cell & tissue research 219 (1981), S. 417-423 
    Details
    ISSN: 1432-0878
    Keywords: Neurohypophysis (Mouse) ; Transplantation ; Pituicytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurohypophysis of donor mice was implanted under the renal capsule of the recipients. The pituicytes survived while the neurosecretory axons disappeared. The ultrastructure of the glial cells was observed seven and nine weeks after transplantation. There were no signs of phagocytotic activity although remnants of axons were still present at seven weeks. The numerous processes of the pituicytes form a network with intercellular spaces wide in younger and narrower in older implants. The cells are connected by desmosomes and gap junctions. Pituicytes as well as blood vessels preserve their organotypic appearance. The transplant thus represents an experimental model for investigations on pituicytes in vivo in the absence of neurosecretory axons.
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    URL: http://dx.doi.org/10.1007/BF00210159
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    Development of the bovine acrosome (1981)
    Springer
    Cell & tissue research 219 (1981), S. 511-524 
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    ISSN: 1432-0878
    Keywords: Acrosome, bovine ; Acrosomal development ; Acrosomal glycoproteins ; Ultrastructure ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study the development of the bovine acrosome was investigated using conventional electron-microscopical techniques as well as the phosphotungstic-acid (PTA) technique (Rambourg 1967) including enzymatic digestion experiments. As in other species and in accordance with previous light-microscopical studies (Clermont and Leblond 1955) four phases of acrosomal differentiation can be discerned: the Golgi-phase, cap-phase, acrosome-phase, and maturation-phase. In the bull no internal pattern of the acrosomal content can be observed, either with conventional uranyl acetate-lead citrate staining or with the PTA-techniques. Our results support the observation in other species (Fawcett et al. 1971) that no intrinsic polymerization or crystallization process of the acrosomal content is responsible for acrosomal shaping. Some of our results suggest the influence of external forces on acrosomal development in the bull. During the cap-phase and the acrosome-phase accumulations of smooth endoplasmic reticulum and a layer of fine filaments can be observed in the Sertoli-cell cytoplasm, immediately adjacent to the developing acrosome. A temporary influence of these structures on acrosomal development seems possible. The PTA-positive staining of the developing bovine acrosome is probably due to the presence of acrosomal glycoproteins; however, our results do not exclude the possibility that molecules other than glycoproteins contribute to the positive PTA-staining of the developing acrosome.
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    URL: http://dx.doi.org/10.1007/BF00209990
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    Electron-microscopic studies on the relationship between the frequency of parathyroid storage granules and serum calcium levels in the rat (1981)
    Springer
    Cell & tissue research 219 (1981), S. 457-467 
    Details
    ISSN: 1432-0878
    Keywords: Parathyroid (Rat) ; Storage granules ; Serum calcium level ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the rat parathyroid, the mean number of storage granules (NSG) per chief cell has been electron-microscopically studied and correlated with the mean serum calcium level (SCL). In animals given 4% CaCl2 plus vitamin D2 for 3 days, SCL is significantly elevated and NSG is increased. When these animals are injected with 2% EDTA, SCL is lowered to 8 mg/dl, but NSG is not affected; in those injected with 4% EDTA, however, SCL declines to a minimum (5.8 mg/dl) after 30 min, and NSG is also decreased. Control SCL are 8.9 mg/dl. These results indicate that storage granules may not be released until SCL is depressed to a certain level. In rats 3 weeks after castration, the chief cells show hyperplastic changes and SCL is at a low concentration (8.0 mg/dl). NSG, however, remains almost within control limits. Castrated animals injected with 4% EDTA show a hypocalcemia and a decrease in NSG, but NSG gradually recovers over a period of 6h. These data suggest that storage granules can be produced even under lower calcium concentrations. It is concluded that storage granules may be constantly produced and stored, and are released only as an emergency supply of hormone.
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    URL: http://dx.doi.org/10.1007/BF00209986
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    Ultrastructural study of the sinus gland of the crab, Cardisoma carnifex (1981)
    Springer
    Cell & tissue research 220 (1981), S. 293-312 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Ultrastructure ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sinus gland of Cardisoma carnifex was examined by light and transmission electron microscopy. This neurohemal organ is composed primarily of enlarged, branching axon terminals with numerous finger-like projections, which act as storage and release sites for neurohormones that are assumed to be contained in membrane-bound, electron-dense neurosecretory granules. Also present in the sinus gland are glial cells with cytoplasmic processes which form elaborate wrappings around neurosecretory terminals, and an acellular fibrillar lining of the branching blood sinus. Six types of neurosecretory terminals are identified on the basis of granule size, granule density, and density of the axoplasmic matrix. Images supporting the hypothesis of release of neurosecretory material by exocytosis from terminals abutting the blood sinus lining are found. Large multilamellate bodies appear in terminals depleted of neurosecretory granules and may be involved in the recycling of granule membrane.
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    URL: http://dx.doi.org/10.1007/BF00210510
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    Morphologic development of neonatal rat pinealocytes in monolayer culture (1981)
    Springer
    Cell & tissue research 220 (1981), S. 337-347 
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    ISSN: 1432-0878
    Keywords: Pineal ; Monolayer culture ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological development of pinealocytes maintained in monolayer culture, without the neural and humoral effects present in the developing rat has been studied and compared with the development that occurs in vivo. Pinealocytes in 5 day cultures contained organelles that were similar to those present in the pineals of intact 5 day old rats. However, light and dark cells were not noted in culture, and the cultured cells did not have the dense granules noted in vivo. As pinealocytes developed in culture, cytoplasmic processes increased in length and number. By 21 days of culture age, synaptic ribbons were found to have decreased in number, the difference between light cell and dark cell cytoplasm had become more prominent, and dense-cored vesicles had become more numerous, just as in the developing gland in vivo. These results suggest that the complex neural and humoral factors impinging upon the developing neonatal pineal in the intact animal may not be necessary for some aspects of its ultrastructural differentiation.
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    URL: http://dx.doi.org/10.1007/BF00210513
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    Ultrastructural study of Kupffer cells in teleost liver under normal and experimental conditions (1981)
    Springer
    Cell & tissue research 220 (1981), S. 387-391 
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    ISSN: 1432-0878
    Keywords: Kupffer cells ; Liver ; Sinusoids ; Teleost ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Kupffer cells in the liver of the teleost fish, Pimelodus maculatus, are attached by desmosomes to the endothelial cells lining the sinusoids. These provide a strong attachment allowing them to resist the passage of blood. Following perfusion with India ink, both endothelial and Kupffer cells ingest India ink particles by pinocytosis and micropinocytosis. It is suggested that both cell types may represent two different functional states of the same cell.
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    URL: http://dx.doi.org/10.1007/BF00210516
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    Fine structural study of the statocysts in the veliger larva of the nudibranch, Rostanga pulchra (1981)
    Springer
    Cell & tissue research 214 (1981), S. 67-80 
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    ISSN: 1432-0878
    Keywords: Statocyst ; Larva ; Nudibranch ; Sensory cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The two statocysts of the veliger larva of Rostanga pulchra are positioned within the base of the foot. They are spherical, fluid-filled capsule that contain a large, calcareous statolith and several smaller concretions. The epithelium of the statocyst is composed of 10 ciliated sensory cells (hair cells) and 11 accessory cells. The latter group stains darkly and includes 2 microvillous cells, 7 supporting cells, and 2 glial cells. The hair cells stain lightly and each gives rise to an axon; two types can be distinguished. The first type, in which a minimum of 3 cilia are randomly positioned on the apical cell membrane, is restricted to the upper portion of the statocyst. The second type, in which 9 to 11 cilia are arranged in a slightly curved row, is found exclusively around the base of the statocyst. Each statocyst is connected dorso-laterally to the ipsilateral cerebral ganglion by a short static nerve, formed by axons arising from the hair cells. Ganglionic neurons synapse with these axons as the static nerve enters the cerebral ganglion. The lumen of the statocyst is continuous with a blind constricted canal located beneath the static nerve. A diagram showing the structure of the statocyst and its association with the nervous system is presented. Possible functions of the statocyst in relation to larval behavior are discussed.
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    URL: http://dx.doi.org/10.1007/BF00235145
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    Control of the pars intermedia of the lizard, Anolis carolinensis (1981)
    Springer
    Cell & tissue research 214 (1981), S. 1-22 
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    ISSN: 1432-0878
    Keywords: Neuro-intermediate lobe ; Anolis carolinensis ; Horseradish peroxidase ; Ultrastructure ; Extracellular space ; Ependymal cells ; Stellat cells ; Secretory cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of the tracer substance horseradish peroxidase (HRP, Mw 40,000) in the neuro-intermediate lobe of the lizard, Anolis carolinensis, was studied at various time intervals (13 min to 24 h) after vascular injection. HRP rapidly entered the extracellular lumen of the neural lobe, but did not penetrate into the third ventricle. The tracer was found in micropinocytotic vesicles (MPVs) of ependymal cells within 13 min after injection. The number of cellular inclusions containing HRP increased during the period of observation (24 h). The tracer was sparsely taken up by aminergic and peptidergic nerve terminals of the external layer. After transection of the hypophysial stalk, numerous dense, labelled droplets were found in the peptidergic terminals, and the number of labelled inclusions in ependymal cells increased. MPVs were frequently found in extensions of stellate cells of the intermediate lobe, and endocytotic vacuoles (EVs) developed especially in the perikaryon. HRP was also found in large cisternae of the secretory cells, appearing predominantly towards the perivascular septum (PVS). These cisternae were found to communicate with the extracellular lumen, probably representing a system of the extracellular space extending into the secretory cell. After transection of the hypophysial stalk, there was an increase in the number of small EVs in secretory cells of the intermediate lobe. The results are discussed in terms of MSH-release regulation and possible participation of the extracellular lumen, glial and stellate cells in the transport of regulating factors and secretory material.
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    URL: http://dx.doi.org/10.1007/BF00235140
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    Fine structure of the cirri and a possible mechanism for their motility in stalkless crinoids (Echinodermata) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 207-217 
    Details
    ISSN: 1432-0878
    Keywords: Echinoderm ; Filament bundles ; Motility ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Crinoid cirri are jointed appendages that can slowly bend and straighten. The structures causing each cirrus to move have not been identified unequivocally by light microscopy; therefore, we examined them by electron microscopy. No muscle cells were found, but a probable contractile apparatus was demonstrated in the cytoplasm of epithelial cells lining the oral and aboral coeloms running the length of the cirrus. The presumed contractile apparatus is a bundle of 5 nm filaments oriented parallel to each other and to the long axis of the appendage. We have proposed that contractile shortening of the coelomic epithelia bends the cirrus in an aboral direction, since the fulcral articulations of the skeletal ossicles are oral to the contractile tissue; this active bending is presumably opposed by an elasticity of the oral ligaments, which seem to straighten the cirrus. It is possible that ligaments of the cirrus may undergo neurosecretion-mediated changes in consistency that could lock the appendage into a rigid state; however, active contraction by the ligaments appears unlikely.
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    URL: http://dx.doi.org/10.1007/BF00235158
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    Seasonal changes in ultrastructure of brown adipose tissue in the common shrew (Sorex araneus L.) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 623-632 
    Details
    ISSN: 1432-0878
    Keywords: Brown adipose tissue ; Ultrastructure ; Seasonal changes ; Shrew (Sorex)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Seasonal changes have been detected in the ultrastructure of brown adipose tissue (BAT) of the common shrew, Sorex araneus (a true non-hibernator) living under natural conditions and collected at the time when the most representative growth phase of the animal for the given season could be expected. In summer and autumn, BAT is characterized by the presence of large, regular, spherical lipid droplets and mitochondria closely adhering to one another. During winter, mitochondria possess densely packed cristae and are dispersed in the cytoplasm, sometimes invaginating into lipid droplets; the latter are diminished and often irregular in contour. The BAT in winter specimens is distinguished also by a large amount of blood capillaries penetrating the tissue. In spring, mitochondria of BAT are found more frequently adhering to each other, and are characterized by loosely arranged cristae. In addition to the spherical lipid droplets, agglomerations of lipid material may be found in the cytoplasm. The observed seasonal fluctuations in the ultrastructure of BAT in the shrew correspond to the metabolic rhythm of this animal. The latter point is discussed.
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    URL: http://dx.doi.org/10.1007/BF00233501
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    Fine structure and function of interrenal (adrenocortical) cells of dexamethasone-treated trout (Salmo fario L.) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 641-649 
    Details
    ISSN: 1432-0878
    Keywords: Adrenocortical cells ; Trout ; Ultrastructure ; Dexamethasone ; Cortisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the interrenal (adrenocortical) cells of trout (Salmo fario L.) was studied after dexamethasone treatment. A procedure for identifying and isolating interrenal tissue fragments from the surrounding head kidney tissue prior to their preparation for electron microscopy is described. The peripheral plasma cortisol concentrations were measured in order to evaluate the steroidogenic activity of this tissue. The interrenal cells of control animals contain numerous mitochondria with tubular cristae, and a well developed and highly organized smooth endoplasmic reticulum (SER). The scarcity, or absence, of lipid droplets contrasts markedly with the abundance of SER. Treatment with dexamethasone results in a decrease steroidogenic activity of the interrenal cells, as indicated by the fall in plasma cortisol concentrations. The interrenal cells are small, but still contain numerous mitochondria. The SER is poorly developed, but masses of densely intermeshed smooth cisternae subsist. Lipid droplets do not accumulate in these cells; this peculiarity is discussed in connection with the virtual absence of liposomes in teleost interrenal cells.
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    URL: http://dx.doi.org/10.1007/BF00233503
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    Fine structural indications of an osmoregulatory function of the “gills” in terrestrial isopods (Crustacea, Oniscoidea) (1981)
    Springer
    Cell & tissue research 214 (1981), S. 663-666 
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    ISSN: 1432-0878
    Keywords: Terrestrial isopods ; Gills ; Ultrastructure ; Smooth endoplasmic reticulum ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In all species of Oniscoidea investigated the epithelial cells of the “gills” (=endopodites of pleopods) show the ultrastructural organization of transporting epithelia. Therefore it is assumed that also in the terrestrial isopods the pleopods are involved in respiration as well as osmoregulation.
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    URL: http://dx.doi.org/10.1007/BF00233506
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    An analysis of the integrity of the brachial motor unit in the dystrophic chick embryo (1981)
    Springer
    Cell & tissue research 215 (1981), S. 537-545 
    Details
    ISSN: 1432-0878
    Keywords: Chick embryo ; Muscular dystrophy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In New Hampshire chickens, the primary clinical symptom of dystrophy is limitation of wing motility. Examination of the brachial-level motor unit in chick embryos homozygous for dystrophy reveals abnormalities in both muscular and neural components. Wing motility in these embryos is abnormal as early as six days, and there is a corresponding lack of differentiation of the pectoralis major muscle. The findings suggest that delayed development of brachial-level neuronal pathways is responsible for the decreased wing motility and early degeneration of the pectoral muscle.
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    URL: http://dx.doi.org/10.1007/BF00233530
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    The rat pituitary cleft: A correlated study by scanning and transmission electron microscopy (1981)
    Springer
    Cell & tissue research 215 (1981), S. 515-529 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary ; Rathke's cleft ; Ultrastructure ; Scanning electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary SEM reveals that the inner surface of the pituitary cleft is lined by a continuous layer of marginal cells possessing microvillous and ciliated apical surfaces. The ciliated cells are more numerous on the posterior side (toward the pars intermedia) than on the anterior side of the cleft (toward the pars distalis). In contrast small infoldings (crypts) were occasionally noted only on the marginal layer covering the distal part of the hypophysis. In some areas of the cleft the surface features of the marginal cells are rather similar to the epithelial cells populating the upper parts of the respiratory tract in their topography and distribution. In other regions they also show striking similarities with the ependymal cells (tanycytes) lining the lateral recesses of the 3rd ventricle and the infundibular process with which the pituitary cleft has a very close topographical relationship. The parenchymal cells of the pars distalis are closely related to the flattened marginal cells of the cleft. The intercellular spaces of the pars distalis form a three-dimensional labyrinthic series of cavities continuous with the submarginal spaces of the cleft. Further SEM and TEM results demonstrate that the majority of the microvillous marginal cells lining both sides of the cleft possess surface features such as bulbous protrusions, laminar evaginations and large cytoplasmatic vacuoles, which are very likely the expression of an active transport of fluids. On the basis of these results it is concluded that the fluid-like material (colloid) present in the pituitary cleft is mainly derived from the fluids contained in the lacunar spaces of the pars distalis. Thus, marginal cells by absorbing fluids from the cleft by active endocytosis, may transport to the pars intermedia material (or hormones) produced in the distal part of the gland and vice versa. The cilia present on many marginal cells, based on their 9+2 tubular pattern, possess a kynetic role. This is very similar to that shown by the ciliated cells of the ependyma lining the brain ventricles. The occurrence of ciliated cells within the pituitary parenchyma (mainly in the follicles) suggests that they probably arise from the ciliated cells populating the marginal layer of the cleft and with which the parenchyma cells are closely related.
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    URL: http://dx.doi.org/10.1007/BF00233528
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    Multinucleate Sertoli cells in aged human testis (1981)
    Springer
    Cell & tissue research 217 (1981), S. 259-266 
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    ISSN: 1432-0878
    Keywords: Sertoli cells ; Multinucleate cells ; Testis ; Ultrastructure ; Old age ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present investigation documents morphological characteristics of human Sertoli cells of aged males. Testicular material was obtained from 35 patients (age 62–84 years) with carcinoma of the prostate who had received no previous anticancer therapy. As revealed by light and electron microscopy the appearance of the germinal epithelium showed great individual variations. In all cases examined, however, the occurrence of multinucleate Sertoli cells was a common finding. In seminiferous tubules with intact spermatogenesis these cells closely resembled the normally occurring variants, whereas they displayed features reminiscent of immaturity in the absence of germ cells. It is hypothesized that the nuclei of Sertoli cells in the special situation of aging may resume the capacity to divide, an ability normally restricted to immature cells. Thus, mitosis without subsequent cytokinesis might be an explanation for the formation of multinucleate Sertoli cells.
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    URL: http://dx.doi.org/10.1007/BF00233579
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    Ultrastructure of neurons in the ventromedial nucleus or the hypothalamus in ovariectomized rats with or without estrogen treatment (1981)
    Springer
    Cell & tissue research 217 (1981), S. 451-470 
    Details
    ISSN: 1432-0878
    Keywords: Ventromedial nucleus ; Ultrastructure ; Estrogen effects ; Secretory product ; Lordosis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the ventrolateral and dorsomedial subdivisions of the ventromedial nucleus (VMN) of the hypothalamus was examined in ovariectomized/control and ovariectomized/estrogen-treated rats to compare neurons of these areas to other neurons (specifically the ventrolateral thalamus), and to determine the effects of estrogen on these cells. The neurons of the VMN contain a large nucleus with a prominent nucleolus, rough endoplasmic reticulum (RER), polysomes, a Golgi complex, coated, uncoated and dense-cored vesicles, lysosome-like bodies, inclusion bodies, multivesicular bodies, whorl bodies and myelin figures. Similar organelles were present in the neurons of the ventrolateral thalamus, although polysomes were more prominent, and the cells lacked dense-cored vesicles in the perikarya. Differences in the cells of the VMN between ovariectomized/control and ovariectomized/estrogen-treated rats included a more conspicuous stacking of the RER and greater number of dense-cored vesicles in the estrogen-treated group in both the ventrolateral and dorsomedial subdivisions. In both areas the differences were statistically significant, although more marked in the ventrolateral subdivision. In both VMN subdivisions, the increased stacking of the RER could be correlated with the greater number of dense-cored vesicles and may reflect increased biosynthesis of a secretory product.
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    URL: http://dx.doi.org/10.1007/BF00219357
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    Morphological and histochemical study of the endometrial effects of Ovral in the baboon (1981)
    Springer
    Cell & tissue research 217 (1981), S. 611-624 
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    ISSN: 1432-0878
    Keywords: Endometrium ; Baboon ; Oral contraceptive ; Ultrastructure ; Autophagic vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an effort to better understand changes induced by hormonal contraceptives, a group of female baboons were administered Ovral for a period of 9 months. During this time the endometrium was sampled by transcervical uterine biopsy from both the treated animals and from a control group. The biopsies were all obtained between 10 and 14 days of the treatment cycle or the normal menstrual cycle. The endometrial glandular cells from the treated animals exhibited an accelerated maturation compared with the controls. Ultrastructurally this was reflected by increased cell size, numerous long, slender microvilli on the apical membranes, and increased development of the Golgi complex. Differences were also observed in the predominant type of granule seen in the apical cytoplasm. After 3 and 6 months of treatment with Ovral, no significant differences were noted between groups or between animals within a group. However, after 9 months of treatment, the endometrium displayed differences from the earlier experimental groups as well as individual variations. The functional correlates of these observations are discussed and compared to human endometrium.
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    URL: http://dx.doi.org/10.1007/BF00219368
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    The reorganization of subcellular structure in muscle undergoing fast-to-slow type transformation (1981)
    Springer
    Cell & tissue research 220 (1981), S. 449-471 
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    ISSN: 1432-0878
    Keywords: Muscle ; Fiber type ; Ultrastructure ; Stereology ; Stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transformation of fast-twitch into slow-twitch skeletal muscle was induced in adult rabbits by chronic low-frequency stimulation and studied at the ultrastructural level. With the use of stereological techniques, a time course was established for changes in mitochondrial volume, sarcotubular system, and Z-band thickness for periods of stimulation ranging from 6 h to 24 weeks. T-tubules, terminal cisternae, and sarcoplasmic reticulum decreased at an early stage and reached levels typical of slow muscle after only 2 weeks of stimulation. Transformation of Z-band structure took place between 11/2 and 3 weeks after the onset of stimulation. Mitochondrial volume increased several fold over the first 3 weeks of stimulation, and fell rapidly after 7 weeks, although it still remained above the levels typical of slow muscle. Although there was no sign of degradation and regeneration of the muscle fibers themselves, considerable structural reorganization was evident at the subcellular level after 1 week of stimulation. The fibers passed through a less well organized transitional stage in which fibers could not be assigned to a normal ultrastructural category. After 3 weeks all of the stimulated fibers could be assigned to the normal slow-twitch category although some subcellular irregularities persisted even after 24 weeks. The ultrastructural alterations are discussed in relation to functional and biochemical changes in the whole muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216750
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  • 92
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    Structural changes in the pars intermedia of the cichlid teleost Sarotherodon mossambicus as a result of background adaptation and illumination (1981)
    Springer
    Cell & tissue research 220 (1981), S. 561-571 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; MSH ; Background adaptation ; Sarotherodon mossambicus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The MSH producing cells in the pars intermedia of Sarotherodon mossambicus have been shown to be involved in background adaptation processes. Reflected light received by the eyes affects the activity of these cells. In the present study the hypothesis has been tested that also the pineal organ, as a second photoreceptor, is involved in regulation of the metabolic activity of the MSH cells. The pineal organ appears to contain photoreceptor cells and is considered to be capable of transferring information about light conditions to the animal. Removal of the pineal organ of fish kept on a black background has no effect on activity of MSH cells, whereas the activity of these cells in fish kept in darkness is increased. Thus it seems that the pineal organ exercises its influence on MSH cells only in darkness and that this influence results in a reduced activity of these cells. It is therefore concluded that the metabolic activity of MSH cells is inhibited not only by reflected light received by the eyes, but also by the action of the pineal organ as a result of the absence of illumination. No structural signs of secretory activity can be observed in the pineal, which might indicate synthesis or release of substances like melatonin. However, administration of melatonin reduces the activity of MSH cells. Neither pinealectomy nor treatment with melatonin has any influence on the second cell type of the pars intermedia, the PAS positive cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216760
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    An ultrastructural and histochemical study of the axial musculature in the African lungfish (1981)
    Springer
    Cell & tissue research 220 (1981), S. 599-609 
    Details
    ISSN: 1432-0878
    Keywords: Axial musculature ; Lungfish ; Histochemistry ; Ultrastructure ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Red, intermediate, and white axial muscle fibres of African lungfish were studied using histochemical techniques and electron microscopy. Gross dissection revealed the presence of a small wedge of red coloured muscle along the lateral line. This wedge was shown by histochemical demonstrations of lactate and succinate dehydrogenases, of adenosine triphosphatases, and of lipid to be composed of a mosaic of red and intermediate fibres measuring 23.63 and 34.30 μm in average diameter, respectively. The bulk of the myotome was composed of white fibres having an average diameter of 67.35 μm. Mitochondrial density, capillarity and lipid content were very low for all fibres. These data suggest that the axial musculature is geared primarily for anaerobic function. The mosaic arrangement of fibres, and the lack of a subsarcolemmal band of mitochondria suggests that the lungfish have a muscle organisation that is transitional between lower vertebrates and amphibians.
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    URL: http://dx.doi.org/10.1007/BF00216763
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    Ultrastructure of splenic white pulp of the turtle, Mauremys caspica (1981)
    Springer
    Cell & tissue research 220 (1981), S. 845-855 
    Details
    ISSN: 1432-0878
    Keywords: Spleen ; Lymphoid tissue ; Reptiles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of splenic tissue of non-immunized turtles, Mauremys caspica, shows two areas, namely, the white pulp which is lymphoid in nature, and the red pulp which is formed by cell cords and sinusoids. Between both areas there is always a marginal zone with gaps through which cells leak. In the white pulp, there are two blood vessel types; one with muscled walls, and the other showing thinner walls sheathed by reticular cells. Reticular cells constitute a network where there occur dendritic macrophages, lymphoblasts and small and medium lymphocytes. Mature plasma cells are scarce in the white pulp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210466
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  • 95
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    Ultrastructure of the jugular body of Rana pipiens (1981)
    Springer
    Cell & tissue research 221 (1981), S. 193-202 
    Details
    ISSN: 1432-0878
    Keywords: Jugular bodies ; Lymphoid organs ; Amphibians ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The jugular bodies in adult Rana pipiens, are surrounded by a capsule of mesothelium and connective tissue, and their parenchyma consists of cell cords arranged in a sinusoidal network. The cell cords are formed by irregular reticular cells, showing numerous filaments and joined together by zonulae adhaerents. The intercellular spaces are filled by reticular fibres and free cells. These latter are small and medium lymphocytes, lymphoblasts, and developing and mature plasma cells. Additionally, free macrophages, neutrophils and acidophils also occur. Sinusoidal blood vessels show thin walls with numerous filaments and pinocytotic vesicles. They exhibit a discontinuous basement membrane, and tight junctions frequently occur between endothelial cells. Occasionally, lymphatic vessels are found and the innervation is principally vasomotor, although nerve endings appear remarkably near reticular cells and lymphocytes. The jugular bodies of adult R. pipiens are plasma cell and antibody-forming organs, whose functional significance is discussed in relation to their ultrastructural organization.
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    URL: http://dx.doi.org/10.1007/BF00216581
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  • 96
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    Plasma cells in the ammocoete of Petromyzon marinus (1981)
    Springer
    Cell & tissue research 221 (1981), S. 203-208 
    Details
    ISSN: 1432-0878
    Keywords: Plasma cells ; Spleen ; Ammocoete ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Ce travail démontre pour la première fois l'existence de plasmocytes murs et en développement dans la rate d'ammocètes de Petromyzon marinus non-immunisés. Les plasmocytes se présentent comme des cellules électroniquement denses avec de la chromatine condensée et un grand développement du réticulum endoplasmique granulaire. L'importance de cette découverte apparaît accentuée en relation avec l'évolution du système immunitaire.
    Notes: Summary This study demonstrates for the first time the presence of mature and developing plasma cells in the spleen of non-immunized ammocoetes of Petromyzon marinus. Plasmocytes occur as electron-dense cells with much condensed chromatin and an extensively large developed and dilated rough endoplasmic reticulum. The importance of this finding is emphasized in relation to the evolution of the immune system.
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    URL: http://dx.doi.org/10.1007/BF00216582
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    Distribution of calcium differs in relaxed and contracted myocardial cells of the rat (1981)
    Springer
    Cell & tissue research 221 (1981), S. 295-302 
    Details
    ISSN: 1432-0878
    Keywords: Cardiac muscle cells ; Calcium ; Sarcomere ; Ultrastructure ; Contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Myocardial cells from left ventricles of beating hearts of rats were fixed by immersion in an osmium tetroxide solution containing potassium pyroantimonate to study the electron-microscopic distribution of calcium, the cation being precipitated as an electron-opaque salt (calcium antimonate) by this cytochemical technique. The observed myocytes could be divided into two groups according to their contractile state, evaluated by sarcomere length measurements. In contracted cells (mean sarcomere length 1.43 μm) the intramyoflbrillar precipitate was confined to areas of I-bands bordering the A-bands, the intermyofibrillar space showing scarce content in reaction product. Relaxed cells (mean sarcomere length 1.69 μm) presented a heavy deposition of reaction product over the sarcomeres, the electron-opaque dots being absent on the H and Z bands. The sarcotubular system and mitochondria were also clearly marked by the reaction product. This second pattern of calcium distribution has not been previously described in heart muscle cells and is interpreted as corresponding to the phase of rise of intracellular calcium which is mediated by membrane depolarization. Our results suggest that different bands of heart sarcomeres show different abilities to bind calcium. The I bands retain the cation even in cells under sustained contraction, probably due to their content in calmodulin; Z and M bands are apparently not involved in calcium sequestration, whereas the content in calcium of the A bands seems to be dependent on the contraction-relaxation cycle of heart myocytes.
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    URL: http://dx.doi.org/10.1007/BF00216733
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    Comparison of fast and slow synaptic terminals in lobster muscle (1981)
    Springer
    Cell & tissue research 221 (1981), S. 303-310 
    Details
    ISSN: 1432-0878
    Keywords: Neuromuscular terminal ; Fast synapse ; Slow synapse ; Lobster ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic terminals of fast (FCE) and slow (SCE) excitatory neurons were physiologically identified on separate fibres of one muscle, the closer muscle in lobster claws. The innervation by these identified fibers was demonstrated over long distances (7–21 μm) by examining serial thin sections at periodic intervals. The ultrastructure of each type of innervation was consistent both qualitatively and quantitatively in two separate samples. The FCE innervation is relatively simple in having consistently small-diameter terminals each forming a single long synapse, with few synaptic vesicles, and little if any postsynaptic apparatus. The SCE innervation is more complex in having larger-diameter but more variable terminals forming several short synapses, with many synaptic vesicles and an extensive postsynaptic apparatus. These differences in the size of the synapses and the number of synaptic vesicles parallel differences in transmitter release and fatigue sensitivity characteristic of the two types of innervation. The degree of elaboration of the postsynaptic apparatus may reflect differences in the amount of transmitter taken up after release. Our data reveal for the first time in a single muscle differences between FCE and SCE innervation previously reported in different muscles and in different species.
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    URL: http://dx.doi.org/10.1007/BF00216734
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    Fine structure and function of the prosomal glands of the two-spotted spider mite, Tetranychus urticae (Acari, Tetranychidae) (1981)
    Springer
    Cell & tissue research 221 (1981), S. 339-349 
    Details
    ISSN: 1432-0878
    Keywords: Prosomal glands ; Spider mite ; Tetranychus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The prosomal glands of Tetranychus urticae (Acari, Tetranychidae) were examined light and electron microscopically. Five paired and one unpaired gland are found both in females and males. The silk spinning apparatus consists of paired silk glands which extend laterally on both sides of the esophagus into the pedipalps. There, they enter the terminal silk gland bag which opens into a silk bristle at the apex of the pedipalps. The salivary secretions are formed in three paired glands which have an interconnecting duct, the podocephalic canal. The dorsal podocephalic glands may produce a serous secretion, the anterior podocephalic glands a mucous secretion, and the coxal organ may add a liquid, ion-rich secretion. These secretions pass the podocephalic canal and reach the mouth at the apex of the gnathosome. The function of the paired tracheal organs and the unpaired tracheal gland is still unclear. The tracheal gland may produce a secretion which facilitates the movement of the fused chelicerae and the stylets.
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    URL: http://dx.doi.org/10.1007/BF00216738
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  • 100
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    Electron-microscope study of the dentine-enamel junction of kangaroo (Macropus giganteus) teeth using selected-area argon-ion-beam thinning (1981)
    Springer
    Cell & tissue research 221 (1981), S. 405-419 
    Details
    ISSN: 1432-0878
    Keywords: Teeth (Marsupials) ; Enamel ; Dentine ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transmission electron microscopy of selected-area argon-ion-beam thinned kangaroo (Macropus giganteus) enamel revealed a complex ultrastructure in the region of the dentine-enamel junction (DEJ). Characteristic features were multiple branching of dentinal tubules, rejoining of enamel tubules, elongated defects, extended protrusions of dentine into enamel, two types (A and B) of hypomineralized enamel and a continuity between dentinal and enamel tubules. In the intertubular regions of the DEJ a complex intermingling of finer enamel and dentine crystals, similar to that found in human enamel, was observed. The varicosities observed in the light microscope were a combined optical effect caused by the hypomineralized (type A) enamel and the branching and rejoining of the enamel tubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216744
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