The Development of Fibre-Tracueid Pit Membranes in Pyrus Communis L.

IAWA Journal ◽  
1987 ◽  
Vol 8 (2) ◽  
pp. 134-142 ◽  
Author(s):  
J.R. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Secondary Wall ◽  
Transverse Section ◽  
Pyrus Communis ◽  
Cell Enlargement ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Pyrus Communis L ◽  
Cambial Cells

The development of fibre-tracheid pit membranes in Pyrus communis L. has been studied using transmission electron microscopy. Pit fields in the radial walls of cambial cells in transverse section contain isolated plasmodesmata. As cell enlargement proceeds, groups of plasmodesmata develop within thickenings of the future pit membrane. These thickenings are covered by amorphous, secondary-wall-like material (the torus-like structures found in mature pits by Parameswaran ' Liese, 1981) just prior to the end of differentiation and cytoplasmic autolysis. It is suggested that this cap of material acts as aseal, preventing passage of autolytic enzymes from a dying cell to its living neighbour via the perforations occupied by plasmodesmata.

Ultrastructural and cytological observations of apothecial tissues of Geopyxis carbonaria (Pezizales, Ascomycetes)

1990 ◽  
Vol 68 (2) ◽  
pp. 243-257 ◽  
Author(s):  
James W. Kimbrough ◽  
Jack L. Gibson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Mother Cell ◽  
Secondary Wall ◽  
Cell Stage ◽  
Wall Structures ◽  
Transmission Electron ◽  
Secondary Wall Formation ◽  
Characteristic Features

Cytological observations are made on apothecial tissues of Geopyxis carbonaria, using transmission electron microscopy. Characteristic features of both the medullary and ectal excipula are examined. Changes in ascus apex and wall structures are examined during ascus ontogeny, especially in relation to operculum position and structure. Ultrastructure of septum configuration is observed and compared in the excipulum, ascogenous hyphae, paraphyses, and at the base of young asci. Ascosporogenesis is observed from the ascus mother cell stage and initial spore delimitation until secondary wall formation. The cytological and ultrastructural observations on this species are discussed in relation to their possible taxonomic or phylogenetic value. Key words: ascosporogenesis, Discomycetes, ascospore ultrastructure, septal ultrastructure, cytochemistry.

Structure and Ultrastructure of the Tracheary Elements of Asplenium (Pteridophyta) from the “Yungas”, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (2) ◽  
pp. 227-240 ◽  
Author(s):  
María Luján Luna ◽  
Gabriela Elena Giudice ◽  
María Alejandra Ganem ◽  
Elías Ramón de la Sota
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Maturation Stage ◽  
Tracheary Elements ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Membrane Hydrolysis ◽  
Structure And Ultrastructure ◽  
Scanning Electron

The structure of root and rhizome tracheary cells of Asplenium spp. (Filicales, Pteridophyta) growing in NW Argentina was studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In all cases, tracheary cells consisted of tracheids with various facets, mainly with scalariform pitting. With SEM, intertracheary pit membranes appeared smooth and non porose in most cases. In some instances, porose or web-like to thread-like pit membranes were noticed in rhizome tracheids. Under TEM secondary walls displayed a smooth and uniform appearance. Pit membranes showed a variation in thickness in presumed association with their maturation stage. More mature tracheary cells showed pit membranes with a mesh-like aspect and visible openings or pores. These characteristics are attributed to pit membrane hydrolysis, which facilitates water transport among tracheary cells.

Preparation of Electropolished Transverse Sections of Thin Aluminum Sheet for Transmission Electron Microscopy

1987 ◽  
Vol 115 ◽  
Author(s):  
Steve Smith
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transverse Section ◽  
Aluminum Sheet ◽  
Specimen Preparation ◽  
Ion Milling ◽  
Transmission Electron ◽  
Thin Aluminum ◽  
Time Required

ABSTRACTThe preparation of transverse section TEM foils from thin (0.2 mm to 1.5 mm) aluminum sheet would usually be accomplished by a combination of dimpling and ion milling. Both of these techniques are time consuming. A technique has been developed which allows these transverse section foils to be prepared by electropolishing, which greatly reduces the time required for specimen preparation. This technique also produces far more thin area for examination than a comparable foil which has been dimpled and ion milled, and eliminates artifacts produced by ion milling.

Polymorphism of microtriches in the cysticercoid of Ophryocotyle insignis Lonnberg, 1890 from the limpet Patella vulgata

1983 ◽  
Vol 61 (5) ◽  
pp. 1062-1070 ◽  
Author(s):  
Barbara M. MacKinnon ◽  
Michael D. B. Burt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Anterior Margin ◽  
Transverse Section ◽  
External Surface ◽  
Larval Body ◽  
Patella Vulgata ◽  
Transmission Electron ◽  
Different Types

The mature cysticercoid of Ophryocotyle insignis, from Patella vulgata, was examined using transmission electron microscopy. Eight different types of microtriches were present over the tegument of the larval body and microvilli covered the caudal bladder, or cercomer. Rounded, modified microtriches were present on the external surface of the bladder enclosing the cysticercoid. Microtriches lining the retraction chamber ranged from small triangular projections having an electron-dense ridge along the anterior margin but having no shaft, to more typically shaped, larger microtriches having a cytoplasmic base, electron-dense shaft, and an electron-dense ridge along the anterior margin of the base. The scolex tegument had large robust microtriches which, in transverse section, had many projecting flanges. The microtriches on the rostellum were long and slender. Long, thin microtriches were present amongst the small spines on the suckers and short microtriches were found on the unspined areas of the suckers. Possible functions for the different types of microtriches are suggested and the significance of microvilli on the cercomer is discussed.

scholarly journals DISTRIBUTION OF PHENOLIC COMPOUNDS, PECTINS AND HEMICELLULOSES IN MATURE PIT MEMBRANES AND ITS VARIATION BETWEEN PIT TYPES IN ENGLISH OAK XYLEM (QUERCUS ROBUR)

IAWA Journal ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 402-419
Author(s):  
Jong Sik Kim ◽  
Geoffrey Daniel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phenolic Compounds ◽  
Quercus Robur ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Bordered Pits ◽  
English Oak ◽  
Pectin Epitopes

Although there is considerable information on the chemistry of bordered intervessel pit membranes, little is known on the pit membrane chemistry of other pit types in hardwoods. This study investigated distribution of phenolic compounds, pectins and hemicelluloses in different mature pit membranes of English oak xylem using transmission electron microscopy coupled with cytochemistry and immunocytochemistry. Mature bordered intertracheid (vasicentric)- and tracheid-vessel pits showed presence of xyloglucan and heteromannan (hemicelluloses) epitopes across the pit membrane (except for the annulus regions) with differences in amounts of epitopes between earlywood (EW) and latewood (LW). In contrast, pectin epitopes were detected only in the annulus regions of pit membranes. Unlike bordered pits, half-bordered (tracheary-parenchyma pits) and simple (parenchyma pits) pit membranes were rich in pectin epitopes but lacked heteromannan epitopes, indicating difference in pit membrane chemistry between pit types. Distribution of phenolic compounds also differed between pit types and between EW and LW. LW also showed great variations in distribution of phenolic compounds between vessels. Together, this study demonstrates that there are great variations in pit membrane chemistry between pit types and between EW and LW in English oak xylem.

The Relationship Between Pit Membrane Ultrastructure and Chemical Impregnability of Wood

Holzforschung ◽  
1999 ◽  
Vol 53 (4) ◽  
pp. 341-346 ◽  
Author(s):  
Adya Singh ◽  
Bernard Dawson ◽  
Robert Franich ◽  
Faye Cowan ◽  
Jeremy Warnes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Cell Types ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Before And After ◽  
Ray Cells ◽  
Membrane Ultrastructure ◽  
The Relationship

Summary The woods of Alder and Eucalypt were examined by light microscopy before and after a chemical treatment by the Indurite process to increase the hardness of the wood. The pattern of wood cell impregnation for Alder differed significantly from Eucalypt in some respects. In Alder wood all cell types eg. vessels, fibres and rays, were impregnated in similar proportions. In comparison, in Eucalypt wood the impregnation material was largely confined to ray cells and the lumina of vessels; other cell types were either not impregnated or impregnated in very small numbers. Transmission electron microscopy of Alder and Eucalypt woods suggests that ultrastructural differences in the texture and porosity of pit membranes may be the main reason for the observed differences between these wood species with regard to their impregnability by the impregnation material used.

Ultrastructure of pit membrane dissolution and movement of Xylella fastidiosa through pit membranes in petioles of Vitis vinifera

Botany ◽  
2010 ◽  
Vol 88 (6) ◽  
pp. 596-600 ◽  
Author(s):  
E. Ann Ellis ◽  
George Ray McEachern ◽  
Samantha Clark ◽  
B. Greg Cobb
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Vitis Vinifera ◽  
Causative Agent ◽  
Xylella Fastidiosa ◽  
Vitis Vinifera L ◽  
Cabernet Sauvignon ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Xylem Element

Xylella fastidiosa is the causative agent in Pierce’s disease (PD) in Vitis vinifera L. (grape) vines. Xylella fastidiosa colonizes and disseminates itself from one xylem element to another by dissolution and breach of pit membranes. These studies on naturally infected V. vinifera grown under vineyard conditions document by transmission electron microscopy that there is dissolution and breach of pit membranes by X. fastidiosa in vertical and lateral colonization in PD. These processes were documented in two cultivars of V. vinifera: ‘Syrah’ and ‘Cabernet Sauvignon.’

Zygosporangium and zygospore formation in Phycomyces nitens

1978 ◽  
Vol 56 (1) ◽  
pp. 91-100 ◽  
Author(s):  
K. L. O'Donnell ◽  
S. L. Flegler ◽  
G. R. Hooper
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Secondary Wall ◽  
Wall Layer ◽  
Central Vacuole ◽  
Transmission Electron ◽  
Large Central Vacuole ◽  
Outer Primary

Zygosporangium and zygospore formation in Phycomyces nitens was followed by correlative light microscopy and scanning and transmission electron microscopy. Compatible multibranched zygophores became interlocked by the interdigitation of their lobes. Progametangia grew up from the substratum in pairs and then differentiated into gametangia and tongs-shaped suspensors. Plasmogamy was deferred until the gametangia were delimited. Development of rings of hyaline appendages on the suspensors was concomitant with plasmogamy. The appendages originated from the tertiary suspensor wall layer and ruptured the outer primary and secondary wall layers prior to development of their terminal thornlike processes.Developing zygosporangia contained a large central vacuole and some organelle zonation; however, these features were not discernible in more mature zygosporangia. A reticulum of electron-opaque fluted warts developed within the secondary zygosporangial wall layer. Cryofractured zygosporangia revealed a smooth hyaline zygospore with truncate ends. Wall layer relations of mature zygosporangia and zygospores were presented. Information obtained was correlated with existing ultrastructural observations on zygosporangiogenesis in the Mucorales.

scholarly journals Review of cellular and subcellular changes in the cambium

IAWA Journal ◽  
2013 ◽  
Vol 34 (4) ◽  
pp. 391-407 ◽  
Author(s):  
Peter Prislan ◽  
Katarina Čufar ◽  
Gerald Koch ◽  
Uwe Schmitt ◽  
Jožica Gričar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Weather Conditions ◽  
Cambial Activity ◽  
Wood Formation ◽  
Structural Level ◽  
Structural Modifications ◽  
Transmission Electron ◽  
Cambial Cells ◽  
The Relationship

The commonest approach to studying cambial productivity is conventional light microscopy, which is widely used in wood formation studies. The number of such studies has increased rapidly in the past decade, usually in order to elucidate the relationship between growth and environmental factors. However, some aspects of cambial seasonality are often overlooked or neglected. Observations with transmission electron microscopy provide a more detailed insight into changes occurring on the ultra-structural level in cambial cells. Criteria for defining cambial activity are not yet fully clarified, especially when observing it at different resolutions, i.e., on cellular, subcellular and ultrastructural levels. The goal of this review is to contribute to clarification of the terms mainly used, such as cambial dormancy, reactivation, activity, productivity and transition between different states, resting period and quiescence, which describe structural modifications of cambial cells during the various phases of their seasonal cycle. Based on our own cambium observations on adult beech trees growing at two different elevations, which were made with light and transmission electron microscopy, we discuss the influence of weather conditions on cambial activity and the advantage of the complementary use of different techniques and resolutions.

Transverse microstructure of an oxide scale formed on a 20% Cr–25% Ni–niobium stabilized stainless steel

1987 ◽  
Vol 412 (1842) ◽  
pp. 223-230 ◽  
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Scanning Transmission Electron Microscopy ◽  
Transverse Section ◽  
Silica Layer ◽  
Spinel Oxide ◽  
Transmission Electron ◽  
Scanning Transmission

A transverse section through a scale formed during the oxidation of 20% Cr–25% Ni–niobium stabilized stainless steel, in carbon dioxide, for 4900 h at 825 °C, has been examined by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques have revealed the detailed microstructure and microchemistry of the three discrete silica, rhombohedral and spinel oxide layers comprising the scale. The variation of strain, degree of oxide order and crystallinity are consistent with the growth of the rhombohedral and spinel oxide being by outward cation movement. This is controlled by diffusion through the thin, amorphous silica layer after it has grown laterally between the rhombohedral oxide layer and the steel.

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