Collenchyma in Panicum maximum (Poaceae): localisation and possible role

2003 ◽  
Vol 51 (1) ◽  
pp. 69 ◽  
Author(s):  
Elder A. S. Paiva ◽  
Sílvia R. Machado
Keyword(s):  
Electron Microscopy ◽  
Leaf Blade ◽  
Sudden Change ◽  
Panicum Maximum ◽  
Vascular Bundles ◽  
Serial Sections ◽  
Adaxial Side ◽  
Transition Area ◽  
Transmission Electron ◽  
Phases Of Development

This work relates the occurrence and distribution of collenchyma in Panicum maximum Jacq. P.�maximum leaves were collected at different phases of development and sampled from both the base of the sheath and from the sheath–leaf blade transition area. For the stems, the study was made by using hand-cut sections of the internodal base. In the leaves, analyses of serial sections showed, at the base and sheath–leaf blade transition area, a sudden change of tissue at vascular bundle. The vascular bundles are surrounded by sclerenchyma, both in the sheath and the leaf blade, as well as by fibrous threads that occur on the adaxial side of the central bundles. However, at the base of the sheath and at the sheath–leaf blade transition area, sclerenchyma was substituted for collenchyma. In the stem, the substitution of sclerenchyma associated with vascular bundles for collenchyma occurs at the base of the internode, in the pulvinus region. The analyses from transmission electron microscopy showed the presence of lamellated cell wall and active protoplast in collenchyma cells.

The development of the notochord in the chick embryo, studied by scanning and transmission electron microscopy

Development ◽  
1976 ◽  
Vol 35 (2) ◽  
pp. 383-401
Author(s):  
Mary Bancroft ◽  
Ruth Bellairs
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chick Embryo ◽  
Intercellular Spaces ◽  
Notochordal Cells ◽  
Fibrillar Material ◽  
Transmission Electron ◽  
Phases Of Development ◽  
Scanning Electron

The notochord of the chick embryo between stages 5 and 23 inclusive has been studied by scanning electron microscopy, supplemented by transmission electron microscopy. Three main phases of development are described, and these have been designated: bilaminar; rodlike, unvacuolated; rod-like and vacuolated. The change in shape of the organ from bilaminar to rod-like is accompanied by changes in the shape, orientation and position of the cells, an increase in the complexity of the cell contacts, and the laying down of a basal lamina. The change from the unvacuolated to the vacuolated phase is accompanied by increasing complexity within the cytoplasm. Most of the vacuoles are intracellular and appear empty though some contain a granular material. The notochordal sheath appears to be secreted by the notochordal cells and fine fibrillar material has been seen in the intercellular spaces. By stage 23, most of the notochordal cells have become so highly vacuolated that the cytoplasm has become closely packed around the nucleus.

scholarly journals Comparative Study of Leaf Surface Texture and Ability to Expand of Cured Tobacco

2001 ◽  
Vol 19 (7) ◽  
pp. 333-338
Author(s):  
R Rohr ◽  
A Eberhard ◽  
R Delon ◽  
JP Descombes ◽  
JM Demor
Keyword(s):  
Electron Microscopy ◽  
Leaf Surface ◽  
Point Of View ◽  
Relative Importance ◽  
Palisade Parenchyma ◽  
Adaxial Side ◽  
Objective Criterion ◽  
Transmission Electron ◽  
The Difference ◽  
Expansion Capacity

AbstractTobacco leaf texture, appreciated by the difference of surface roughness of cured leaves, is studies with light microscopy and scanning electron microscopy (SEM). The leaf texture is obviously determined by the presence or absence of conical cellular protuberances on the adaxial side of the leaf. Considering the anatomic point of view, the leaf thickness, always more important when the leaf texture is open, is the only objective criterion which could be associated to the texture. The ultra-structural study with SEM and transmission electron microscopy (TEM) demonstrates that the expansion capacity of tobacco doesn't rely on cytological factors such as cellular reserves or debris. The expansion capacity could be inversely proportional with the relative importance of the mesophyll comparing to palisade parenchyma. On the studied material, no direct relation between the leaf texture and the expansion capacity has been noticed.

scholarly journals Comparative structure of the osmophores in the flowers of Stanhopea graveolens Lindley and Cycnoches chlorochilon Klotzsch (Orchidaceae)

2012 ◽  
Vol 65 (2) ◽  
pp. 11-22 ◽  
Author(s):  
Sebastian Antoń ◽  
Magdalena Kamińska ◽  
Małgorzata Stpiczyńska
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Lipid Droplets ◽  
Secretory Cells ◽  
Vascular Bundles ◽  
Scent Glands ◽  
Euglossine Bees ◽  
Dense Cytoplasm ◽  
Transmission Electron ◽  
Comparative Structure

The structure of the osmophores in <i>Stanhopea graveolens</i> and <i>Cycnoches chlorochilon</i> was studied by means of light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The scent glands are located in the basal part of the labellum. The surface of the osmophores is wrinkled or rugose, which increases the area of fragrance emission. On the surface of the epidermis, remnants of secretion are noticeable in <i>S. graveolens</i>, but these are absent in <i>C. chlorochilon</i>. The osmophore tissue is composed of secretory epidermal cells and several layers of subepidermal parenchyma, and it is supplied by vascular bundles that run in ground parenchyma. The secretory cells have large nuclei, a dense cytoplasm with numerous ER profiles, lipid droplets, and plastids with a substantial amount of starch, which are probably involved in the synthesis of volatile substances. In the cell walls of the osmophore cells, numerous pits with plasmodesmata occur that are likely to take part in symplastic transport of the scent compounds. The structure of the osmophores is similar in both investigated species. Both <i>S. graveolens</i> and <i>C. chlorochilon</i> are pollinated by euglossine bees, and such similarity results from adaptation to effective scent emission and attraction of pollinators.

scholarly journals Software tools for automated transmission electron dmicroscopy

2018 ◽  
Author(s):  
Martin Schorb ◽  
Isabella Haberbosch ◽  
Wim JH Hagen ◽  
Yannick Schwab ◽  
David N Mastronarde
Keyword(s):  
Electron Microscopy ◽  
Software Tools ◽  
Cellular Biology ◽  
Serial Sections ◽  
High Throughput Data ◽  
Volume Imaging ◽  
Transmission Electron ◽  
Increasing Demand ◽  
Multiple Grids ◽  
3D Volume

AbstractIn the recent years, electron microscopy in the life sciences has witnessed increasing demand for high-throughput data collection in both structural and cellular biology. We present a combination of software tools that enable automated acquisition guided by image analysis for a wide variety of Transmission Electron Microscopy applications. Using these tools, we demonstrate dose-reduction in single particle cryo-EM experiments, fully automated acquisition of every single cell in a plastic section and automated targeting of features on serial sections for 3D volume imaging even across multiple grids.

scholarly journals The structure of the spur nectary in Dendrobium finisterrae Schltr. (Dendrobiinae, Orchidaceae)

2012 ◽  
Vol 64 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Magdalena Kamińska ◽  
Małgorzata Stpiczyńska
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Single Layer ◽  
Secretory Cells ◽  
Vascular Bundles ◽  
Nectar Guides ◽  
Floral Nectary ◽  
Transmission Electron ◽  
Secretory Tissue ◽  
The One

To date, the structure of the nectary spur of <i>Dendrobium finisterrae</i> has not been studied in detail, and the present paper compares the structural organization of the floral nectary in this species with the spurs of other taxa. The nectary spur of <i>D. finisterrae</i> was examined by means of light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is composed of a single layer of secretory epidermis and several layers of small and compactly arranged subepidermal secretory cells. The secretory cells have thick cellulosic cell walls with primary pits. The secretory tissue is supplied by vascular bundles that run beneath in ground parenchyma and are additionally surrounded by strands of sclerenchymatous fibers. The flowers of the investigated species displayed morphological features characteristic of bee-pollinated taxa, as they are zygomorphic, creamy-green coloured with evident nectar guides. They also emit a weak but nice scent. However, they possess some characters attributed to bird-pollinated flowers such as a short, massive nectary spur and collenchymatous secretory tissue that closely resembles the one found in the nectaries of certain species that are thought to be bird-pollinated. This similarity in anatomical organization of the nectary, regardless of geographical distribution and phylogeny, strongly indicates convergence and appears to be related to pollinator-driven selection.

scholarly journals Same Serial Section Correlative Light and Energy-filtered Transmission Electron Microscopy

2003 ◽  
Vol 51 (5) ◽  
pp. 605-612 ◽  
Author(s):  
Ying Ren ◽  
Michael J. Kruhlak ◽  
David P. Bazett-Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscope ◽  
High Rate ◽  
Specific Cell ◽  
3D Analysis ◽  
Serial Sections ◽  
Correlative Imaging ◽  
Transmission Electron ◽  
Rate Of Success

Correlative imaging of a specific cell with both the light microscope and the electron microscope has proved to be a difficult task, requiring enormous amounts of patience and technical skill. We describe a technique with a high rate of success, which can be used to identify a particular cell in the light microscope and then to embed and thin-section it for electron microscopy. The technique also includes a method to obtain many uninterrupted, thin serial sections for imaging by conventional or energy-filtered transmission electron microscopy, to obtain images for 3D analysis of detail at the suborganelle level.

Microstructural Evolution in a CeO2-Gd2O3 System

2011 ◽  
Vol 18 (1) ◽  
pp. 162-170 ◽  
Author(s):  
Fei Ye ◽  
Ding Rong Ou ◽  
Toshiyuki Mori
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Microstructural Evolution ◽  
Oxygen Vacancies ◽  
Sudden Change ◽  
Fluorite Structure ◽  
Type Structure ◽  
Defect Clusters ◽  
Structured Matrix ◽  
Transmission Electron

AbstractMicrostructural evolution in a CeO2-Gd2O3 system at atomic and nanoscale levels with increasing Gd concentration has been comprehensively investigated by transmission electron microscopy. When the Gd concentration was increased from 10 to 80 at.%, the phase transformation from ceria with fluorite structure to solid solution with C-type structure was not a sudden change but an evolution in the sequence of clusters, domains, and precipitates with C-type structure in the fluorite-structured matrix. Moreover, the ordering of aggregated Gd cations and oxygen vacancies in these microstructural inhomogeneities developed continuously with increasing Gd concentration. This microstructural evolution can be further described based on the development of defect clusters containing Gd cations and oxygen vacancies.

Fine structure of Classopollis exines

1986 ◽  
Vol 64 (12) ◽  
pp. 3059-3074 ◽  
Author(s):  
John R. Rowley ◽  
Satish K. Srivastava
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Upper Jurassic ◽  
Thin Sheets ◽  
Serial Sections ◽  
Thin Sections ◽  
Band Area ◽  
Transmission Electron ◽  
Oxidative Etching

Serial sections for light microscopy or transmission electron microscopy of two Classopollis pollen tetrads show that the exine structure, except for the nexine, has radially arranged rodlike units interwoven with transverse subunits. The nexine consists of strands or thin sheets except in the equatorial infratectal striate band area, where it is up to ca. 1 μm thick. Nexine is absent in the areas of the distal cryptopore and the subequatorial circumpolar infratectal canal. It is very thin or absent in the tetrad scar. Native contrast and reactivity to stain disappeared on immersion of thin sections in 1 M NaOH or HCl or in water. Reactivity to stains was regained after oxidizing the sections in KMnO4. Reactivity to stains appears to be dependent upon non-sporopollenin molecules embedded within exines. The above immersions remove stain reactive sites. Oxidative etching of sporopollenin exposes new sites. The specimens of Classopollis classoides Pflug studied and illustrated were picked from an Upper Jurassic sample (CRC 31519-2) collected at Osmington Mills locality, Dorset, England.

scholarly journals Variable opacity of glycogen in routine electron micrographs.

1977 ◽  
Vol 25 (9) ◽  
pp. 1069-1073 ◽  
Author(s):  
L E Thornell ◽  
M Sjöström ◽  
U Karlsson ◽  
E Cedergren
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Micrographs ◽  
Periodic Acid ◽  
Frog Muscle ◽  
Nerve Terminals ◽  
Lead Citrate ◽  
Serial Sections ◽  
Transmission Electron ◽  
Reticular Zone

Glycogen in nerve terminals from the reticular zone of frog muscle was identified by transmission electron microscopy of both periodic acid-thiosemicarbazide-silverproteinate treated and UAc-PbCi-stained serial sections. A variable appearance of glycogen in the uranylacetate-lead citrate-stained nerve terminals was seen and is related to the preparative procedure. The study indicates the necessity of cytochemical identification for the assessment of glycogen organization in cells.

Centromere structure and chromosome number in mitosis of the colourless phytoflagellate Polytoma papillatum (Chlorophyceae, Volvocales, Chlamydomonadaceae)

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1249-1254 ◽  
Author(s):  
Klaus Werner Wolf
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chromosome Number ◽  
Higher Plants ◽  
Attachment Site ◽  
Dense Layer ◽  
Mitotic Metaphase ◽  
Serial Sections ◽  
Transmission Electron ◽  
Alternative Approach

Centromere structure is described in mitosis of the unicellular biflagellate alga Polytoma papillatum using transmission electron microscopy. The kinetochores are five-layered elements at the poleward surface of the chromosomes. The five layers consist of three dense plates interspersed by two transparent zones. The polemost dense layer serves as the attachment site for kinetochore microtubules and the innermost dense layer is intimately associated with the chromatin. The five-layered organization of the kinetochore in the alga is unusual. In animals, three-layered kinetochores are the rule. This type has also been found in some algae, while higher plants do not possess striated kinetochores. An attempt was made to determine the chromosome number of P. papillatum. Individual chromosomes could not be recognized with confidence, since there were numerous lateral contacts between the chromosomes throughout mitosis. An alternative approach, however, was successful. Counting the kinetochores in serial sections through mitotic metaphase and anaphase plates revealed a number of 15 chromosomes.Key words: anaphase, kinetochore, metaphase, microtubule.

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