The development, structure, and histochemistry of sclerotia of ectomycorrhizal fungi. I. Pisolithus tinctorius

1985 ◽  
Vol 63 (8) ◽  
pp. 1402-1411 ◽  
Author(s):  
D. J. Grenville ◽  
R. L. Peterson ◽  
Y. Piché
Keyword(s):  
Electron Microscopy ◽  
Experimental Studies ◽  
Pinus Strobus ◽  
Pinus Resinosa ◽  
Pisolithus Tinctorius ◽  
Root Tips ◽  
Outer Cortex ◽  
Transmission Electron ◽  
Development Structure ◽  
Large Deposits

Sclerotia were produced by growing Pisolithus tinctorius (Pers.) Coker and Couch in association with Pinus strobus L. and Pinus resinosa Ait. in plastic growth pouches. Developing and mature sclerotia were collected, fixed, and embedded for light microscopy and scanning and transmission electron microscopy. They were found to consist of an outer pigmented rind, an inner and outer cortex, and a large central medulla. Cortical and medullary areas were comprised of pseudoparenchyma which contained large deposits of glycogen, as well as protein and lipids. The structure of these sclerotia indicates that they are persistent propagules. Sclerotia may be important in nature for the recolonization of root tips after environmental stresses. They may also be useful for storing valuable strains of P. tinctorius and as a source of inoculum for experimental studies.

The development, structure, and histochemistry of sclerotia of ectomycorrhizal fungi. II. Paxillus involutus

1985 ◽  
Vol 63 (8) ◽  
pp. 1412-1417 ◽  
Author(s):  
D. J. Grenville ◽  
R. L. Peterson ◽  
Y. Piché
Keyword(s):  
Structural Characteristics ◽  
Pinus Strobus ◽  
Pinus Resinosa ◽  
Cortical Layer ◽  
Paxillus Involutus ◽  
Tree Roots ◽  
Cortical Cells ◽  
Transmission Electron ◽  
Development Structure ◽  
Large Deposits

Sclerotia of Paxillus involutus (Batsch) Fr. were produced in association with Pinus strobus L. and Pinus resinosa Ait. in plastic growth pouches and on agar-solidified nutrient medium. They were fixed and embedded for light microscopy and scanning and transmission electron microscopy. Sclerotia consisted of an outer pigmented rind, a thin cortical layer, and a large central medulla of isodiametric cells. Large deposits of glycogen, as well as smaller deposits of protein and lipid, were present in medullary and cortical cells. Structural characteristics indicate that these sclerotia are persistent propagules which may function to reinfect tree roots following environmental stresses. Since they can be produced in pure culture, it may be possible to inoculate seedlings directly with sclerotia.

Morphometric analysis of the actions of angiotensin II on renal arterioles and glomeruli

1992 ◽  
Vol 262 (3) ◽  
pp. F367-F372 ◽  
Author(s):  
K. M. Denton ◽  
P. A. Fennessy ◽  
D. Alcorn ◽  
W. P. Anderson
Keyword(s):  
Electron Microscopy ◽  
Angiotensin Ii ◽  
Vascular Resistance ◽  
Morphometric Analysis ◽  
Unit Length ◽  
Average Difference ◽  
Outer Cortex ◽  
Efferent Arteriole ◽  
Transmission Electron ◽  
The Right

To study the effects of angiotensin II on afferent and efferent arteriole diameters and on intraglomerular dimensions, angiotensin II (20 ng.kg-1.min-1) or saline vehicle was infused intravenously for 20 min into anesthetized rabbits pretreated with enalapril. Both kidneys were perfusion fixed (glutaraldehyde), and vascular casts were made of the right kidneys using methacrylate. Morphometric analysis of the left kidneys using transmission electron microscopy revealed no significant effects of angiotensin II within the glomerulus, including the degree of mesangial contraction. The diameters of the afferent and efferent arteriole casts from the right kidneys were measured at 20, 50, and 75 microns from the glomerulus by scanning electron microscopy. In the outer cortex the mean diameters of the afferent and efferent arterioles were 14.1 +/- 0.8 and 9.7 +/- 0.5 microns, respectively, in the angiotensin II-infused rabbits, significantly less than in the control (vehicle) rabbits, 17.0 +/- 0.7 microns (P less than 0.001) and 10.7 +/- 0.4 microns (P less than 0.005), respectively. Calculation of the relative changes in vascular resistance, however, indicated that the effects of angiotensin II on efferent arteriole resistance (average difference 2.4 +/- 1.2 units/microns) were significantly greater per unit length than the effects on afferent arteriole resistance (average difference 0.9 +/- 0.3 units/microns). Thus infused angiotensin II caused greater reduction in afferent arteriolar diameter than in efferent, but the calculated increase in vascular resistance per micron was greater in efferent vessels due to their smaller resting diameter.

Neoformation of halloysite on volcanic glass in a marine environment

Clay Minerals ◽  
1987 ◽  
Vol 22 (2) ◽  
pp. 179-185 ◽  
Author(s):  
T. Imbert ◽  
A. Desprairies
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Marine Environment ◽  
Experimental Studies ◽  
Volcanic Glass ◽  
Marine Environments ◽  
Thin Sections ◽  
Transmission Electron ◽  
Glass Shards

AbstractTransmission electron microscopy of ultramicrotomed thin-sections of Pleistocene and Eocene glass shards revealed the neoformation of (i) illite and (ii) halloysite at the glass periphery. According to previous experimental studies, halloysite neoformation in marine environments can occur on glass shards deposited in Si-rich sediments; an excess of Ca tends to inhibit the reaction.

Human endolymphatic sac: possible mechanisms of pressure regulation

1987 ◽  
Vol 101 (8) ◽  
pp. 768-779 ◽  
Author(s):  
Phillip Ashley Wackym ◽  
Ulla Friberg ◽  
Dan Bagger-Sjöbäck ◽  
Fred H. Linthicum ◽  
Imrich Friedmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Experimental Studies ◽  
Secretory Activity ◽  
Regulatory Mechanisms ◽  
Endolymphatic Sac ◽  
Pressure Regulation ◽  
Transmission Electron ◽  
Normal Human ◽  
Mechanical Factors

AbstractThe ultrastructure of the normal human endolymphatic sac (ES) has been observed by transmission electron microscopy (TEM). The role of the epithelium, the various regions of the subepithelial space and the general anatomy of the ES in pressure regulation were morphologically studied to generate testable hypotheses of human ES function. Light microscopic (LM) and TEM evidence of pressure regulatory mechanisms by endolymph resorption, mechanical factors, and secretory activity are presented. These mechanisms may be useful in designing experimental studies of the ES, and in interpretation of retrospective LM and TEM studies of patients with Meniere's disease.

A Correlated Scanning And Transmission Electron Microscopy Study of Pulmonary Airway Morphology in the Rhesus Monkey

1973 ◽  
Vol 31 ◽  
pp. 618-619
Author(s):  
W. L. Castleman ◽  
D. L. Dungworth
Keyword(s):  
Electron Microscopy ◽  
Rhesus Monkeys ◽  
Experimental Studies ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron ◽  
Critical Point Drying ◽  
Pulmonary Airways ◽  
Structural Differences ◽  
Airway Morphology

Previous research has indicated that there are important differences in the structure of pulmonary airways among various species of mammals and that these structural differences must be taken into consideration when animal models are being used in experimental studies of pulmonary disease. An investigation is being undertaken in this laboratory to characterize airway structure in several species of nonhuman primates and compare that structure with airway structure that has been described in man. The following is a report on studies of lungs from rhesus monkeys.Lungs from adult rhesus monkeys were, fixed via the airways with cacodylatebuffered glutaraldehyde-formaldehyde. Various levels of bronchi and bronchioles were bisected with razor blades. One half of the bisected airway was prepared for scanning electron microscopy by dehydration, critical point drying from CO2, and conductive coating with silver and gold.

Kinetic controls on the formation of metastable phases during the experimentally induced breakdown of chlorite

1993 ◽  
Vol 57 (386) ◽  
pp. 141-156 ◽  
Author(s):  
K. A. Waldron ◽  
G. T. R. Droop ◽  
P. E. Champness
Keyword(s):  
Electron Microscopy ◽  
Grain Boundaries ◽  
Reaction Mechanisms ◽  
Experimental Studies ◽  
Contact Metamorphism ◽  
Reaction Products ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
Chlorite Schist

AbstractThe kinetics and reaction mechanisms of chlorite breakdown have been studied in a series of experiments at conditions similar to those achieved during contact metamorphism (T = 600-725°C P = 1 kbar). Cores of chlorite schist were used as starting material in order to simulate natural metamorphic systems and preserve reaction textures. Reaction products were analysed by electron microprobe, scanning- and transmission-electron microscopy (SEM, TEM). Although the texture of the original chlorite was preserved in experiments run below 680°C talc had replaced chlorite. Olivine and spinel formed along grain boundaries, indicating long-range diffusion of aluminium. Above 680°C the chlorite was replaced by patches of disordered, aluminous pyroxene. Olivine and spinel grew both within the pyroxene and along what are believed to be former chlorite grain-boundaries. Reactions relevant to the observed textures and assemblages are:Thermodynamic calculations show that both of these reactions are metastable in the FeO-MgO-Al2O3-SiO2-H2O system in the P-T range of our experiments. In addition, previous experimental studies and our calculations indicate that the stable reaction is:The absence of cordierite in the run products, and the formation of talc and orthopyroxene while thermodynamically metastable, show that the ease of nucleation of these phases controlled the reaction mechanisms in the early stages.

Mechanical Behavior of Cu-10ni-6Sn Spinodal Alloy

1982 ◽  
Vol 21 ◽  
Author(s):  
T. C. Lee ◽  
S. Shekhar ◽  
A. Vilassakdanont ◽  
K. N. Subramanian
Keyword(s):  
Electron Microscopy ◽  
Deformation Behavior ◽  
Experimental Studies ◽  
Total Elongation ◽  
Modulated Structure ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Internal Stress Field ◽  
Theoretical Results

ABSTRACTExperimental studies on deformation behavior of Cu-10Ni-6Sn spinodal alloy specimens subjected to different aging treatments were carried out at various temperatures ranging from 77°K to 353°K, using a micro-tensile device. It was found that the total elongation was independent of aging time as long as the modulated structure was coherent. Observed slip distribution and activation energy obtained in these investigations are presented. Transmission electron microscopy of deformed specimens showed straight dislocations in as-quenched samples; they were curved and wavy in aged samples. Burgers vector analysis of the dislocations present in the deformed aged samples indicated that they were of mixed character. Preliminary theoretical results on the role of wave-squaring of the internal stress field on CRSS are also presented.

scholarly journals Hemagglutination in gill capillaries of sheepshead, Archosargus probatocephalus (Perciformes: Sparidae), infected by a myxosporidean

2022 ◽  
Vol 31 (1) ◽  
Author(s):  
Carlos Azevedo ◽  
Graça Casal ◽  
Emerson Carlos Soares ◽  
Elsa Oliveira ◽  
Sónia Rocha ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Density ◽  
Intercellular Space ◽  
Experimental Studies ◽  
Parasite Development ◽  
Parasitic Infections ◽  
Physicochemical Processes ◽  
Transmission Electron ◽  
Close Proximity

Abstract During a survey Myxozoa, four specimens of the sheepshead (18 ± 1.5 cm and 59 ± 2.5 g) (Archosargus probatocephalus) were collected in the Ipioquinha river (Maceió/AL). Transmission electron microscopy observations revealed erythrocyte agglutinations in gill capillaries located near spherical cysts containing myxospores of the genus Henneguya. This hemagglutination partially or totally obstructed the gill capillaries. Erythrocytes occurred in close adherence to each other, with a closed intercellular space. A few lysed erythrocytes were observed among agglutinated cells. The reduced lumen of the capillaries was partially filled with amorphous dense homogenous material adhering to the erythrocytes. In addition, heterogeneous masses of irregular lower electron density were observed in the reduced channel of the capillary. The agglutinated erythrocytes appeared dense and homogenous, lacking cytoplasmic organelles. The nuclei had the appearance of normal condensed chromatin masses, generally without visible nucleoli. This occurrence of hemagglutination only in the capillaries located in close proximity to the developing myxozoan cysts suggests that parasite development may be a factor triggering erythrocyte agglutination. This is supported by previous experimental studies that showed a probable correlation between parasitic infections and hemagglutination. Nonetheless, further studies are necessary in order to better understand the physicochemical processes involved in this phenomenon.

Morphological characteristics of linear (AB)n multiblock copolymers near the order-disorder transition

1994 ◽  
Vol 52 ◽  
pp. 440-441
Author(s):  
Richard J. Spontak ◽  
Jonathan H. Laurer ◽  
Steven D. Smith ◽  
Arman Ashraf ◽  
Jon Samseth
Keyword(s):  
Electron Microscopy ◽  
Small Angle Neutron Scattering ◽  
Experimental Studies ◽  
Morphological Characteristics ◽  
Multiblock Copolymers ◽  
Chain Packing ◽  
Molecular Conformations ◽  
Disorder Transition ◽  
New Class ◽  
Transmission Electron

Linear (AB)n multiblock copolymers constitute a new class of copolymers which order into periodic morphologies when the A and B blocks are sufficiently incompatible. Unlike diblockcopolymers (n=1), perfectly alternating multiblock copolymers with n>1 possess midblocks which are capable of adopting either looped or bridged conformations (see Fig. 1). Coexistence of looped and bridged midblocks with non-uniformly stretched endblocks poses an intriguing problem with regard to chain packing and elasticity. Previous theoretical and experimental studies of multiblock copolymers in the strongsegregation regime, wherein repulsive A-B interactions dominate, have demonstrated that, due to the 22(n-1) molecular conformations available, linear multiblock copolymers differ considerably from their AB diblock and ABA triblock analogs in terms of phase stability, microstructural dimensions, and macroscopic properties. In the present work, transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) have been employed in concert to study the morphological features of weakly-segregated (AB)n multiblock copolymers near the order-disorder transition.

scholarly journals A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 878
Author(s):  
Hasti Vahidi ◽  
Komal Syed ◽  
Huiming Guo ◽  
Xin Wang ◽  
Jenna Laurice Wardini ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Experimental Studies ◽  
Atomic Scale ◽  
Polycrystalline Materials ◽  
Structure Property ◽  
Ceramic Oxides ◽  
Structure Property Relationships ◽  
Transmission Electron ◽  
Scanning Transmission

Interfaces such as grain boundaries (GBs) and heterointerfaces (HIs) are known to play a crucial role in structure-property relationships of polycrystalline materials. While several methods have been used to characterize such interfaces, advanced transmission electron microscopy (TEM) and scanning TEM (STEM) techniques have proven to be uniquely powerful tools, enabling quantification of atomic structure, electronic structure, chemistry, order/disorder, and point defect distributions below the atomic scale. This review focuses on recent progress in characterization of polycrystalline oxide interfaces using S/TEM techniques including imaging, analytical spectroscopies such as energy dispersive X-ray spectroscopy (EDXS) and electron energy-loss spectroscopy (EELS) and scanning diffraction methods such as precession electron nano diffraction (PEND) and 4D-STEM. First, a brief introduction to interfaces, GBs, HIs, and relevant techniques is given. Then, experimental studies which directly correlate GB/HI S/TEM characterization with measured properties of polycrystalline oxides are presented to both strengthen our understanding of these interfaces, and to demonstrate the instrumental capabilities available in the S/TEM. Finally, existing challenges and future development opportunities are discussed. In summary, this article is prepared as a guide for scientists and engineers interested in learning about, and/or using advanced S/TEM techniques to characterize interfaces in polycrystalline materials, particularly ceramic oxides.

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