Some ultrastructural aspects of Crithidia guilhermei n.sp. isolated from Phaenicia cuprina (Diptera: Calliphoridae)

1986 ◽  
Vol 64 (12) ◽  
pp. 2837-2842 ◽  
Author(s):  
Maurilio J. Soares ◽  
Reginaldo P. Brazil ◽  
Amilcar Tanuri ◽  
Wanderley de Souza
Keyword(s):  
Freeze Fracture ◽  
Kinetoplast Dna ◽  
Microscopical Level ◽  
Thin Sections ◽  
Crithidia Luciliae ◽  
Transmission Electron ◽  
Light Microscopical Level ◽  
Attachment Region ◽  
Phaenicia Sericata ◽  
A New Species

A flagellate trypanosomatid was isolated from the fly Phaenicia cuprina captured in Rio de Janeiro, Brazil. It grows well in liver infusion – trypticase medium, in the form of choanomastigotes, typical of the genus Crithidia. Morphometrical data obtained at the light microscopical level indicated that the new isolated Crithidia is smaller than Crithidia luciliae, a parasite isolated from Phaenicia sericata. Transmission electron microscopy of thin sections revealed that this trypanosomatid has a flagellar pocket divided into two compartments, one basal and the other apical, separated by a region of attachment of the flagellum to the cell body. The attachment region was characterized in freeze-fracture replicas. The flagellate has a compact kinetoplast DNA network. As in endosymbiote-containing trypanosomatids previously described, no subpellicular microtubules were seen in the regions where the mitochondria touched the plasma membrane, although no endosymbiotes were found in this flagellate. Electrophoretic mobility of six enzymes showed that the parasite could not be grouped in any of the isoenzymic pattern groups of other Crithidia spp. These observations indicate that the trypanosomatid isolated from P. cuprina is a new species of Crithidia. The flagellate is described as Crithidia guilhermei n.sp.

A quick-frozen, freeze-fracture and deep-etched study of the cuticle of adult forms of Strongyloides venezuelensis (Nematoda)

Parasitology ◽  
1995 ◽  
Vol 111 (4) ◽  
pp. 523-529 ◽  
Author(s):  
A. M. B. Martinez ◽  
W. De Souza
Keyword(s):  
Body Wall ◽  
Amorphous Matrix ◽  
Freeze Fracture ◽  
The Body ◽  
Fibrous Layer ◽  
Thin Sections ◽  
Parallel Lines ◽  
Transmission Electron ◽  
Strongyloides Venezuelensis ◽  
Ordered Array

SUMMARYThe cuticle of adult forms of Strongyloides venezuelensis was studied by routine transmission electron microscopy, conventional freeze-fracture and also using quick-freeze and deep-etch techniques. In routine thin sections the cuticle of S. venezuelensis comprises 7 layers: epicuticle, outer cortical, inner corticcal, external medial, internal medial, fibrous and basal. Observation of replicas of specimens fractured across the thickness of the body wall, revealed at the epicuticle an ordered array of particles accompanying the cuticular annulations. At the level of the cortical and medial layers we observed few scattered particles embedded in an amorphous matrix without a particular arrangement. The fibrous layer was represented by several parallel lines of ordered particles of similar size. In tangentially fractured specimens, the epicuticle cleaves readily exposing 2 faces, one exhibiting intramembranous particles without any particular arrangement, immersed in a smooth matrix (P face), and the other showing depressions and very few particles (E face). In replicas of fractures submitted to etching, we observed at the level of the cortical, medial fibrous and basal layers an interconnecting fibrous and globous structure which was organized in a different direction at the fibrous layer. The association of freeze-fracture to deep-etch technique revealed the internal structural organization of the cuticle layers showing details that were not seen before using conventional freeze–fracture technique.

Ultrastructure of the dormant and germinating sporangiospore of Phascolomyces articulosus (Mucorales)

1978 ◽  
Vol 56 (7) ◽  
pp. 747-753 ◽  
Author(s):  
P. Jeffries ◽  
T. W. K. Young
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Freeze Fracture ◽  
Spore Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Transmission Electron ◽  
Sporangial Wall ◽  
Scanning Electron

Using results obtained with light and scanning electron microscopy of critical-point-dried material and transmission electron microscopy of carbon replicas and freeze-fracture and ultra-thin sections, the structure and germination of the sporangiospore of Phascolomyces articulosus Boedijn is described. The sporangial wall is trilaminate and the ornamented spore wall is two layered. During germination, a new wall layer develops between the plasmalemma and the original spore wall. Sporangial structure is related to that of other members of the Thamnidiaceae and the use of germinating spores of P. articulosus for infection studies of the mycoparasite Piptocephalis unispora is indicated.

Intercellular junctions in the larval epidermis of the colonial ascidian Distaplia occidentalis: a thin-section and freeze-fracture examination

1986 ◽  
Vol 64 (1) ◽  
pp. 112-117 ◽  
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Epidermal Cells ◽  
Cellular Membranes ◽  
Colonial Ascidian ◽  
Thin Sections ◽  
Intramembranous Particles ◽  
Transmission Electron ◽  
Columnar Cells

The larval epidermis of the colonial ascidian Distaplia occidentalis is a unilayered epithelium consisting of squamous and cuboidal or low columnar cells. The epidermal cells are laterally folded and interdigitated or overlapped. The occluding (tight) junctions and the close (gap) junctions that join the epidermal cells have been examined by transmission electron microscopy. In thin sections, the occluding junction is represented by focal fusions of the apposed plasmalemmata. Freeze-fracture replicas of the occluding junction show linear, anastomosing arrays of intramembranous particles on the protoplasmic faces of the cellular membranes. In thin sections of the close junction, the apposed plasmalemmata are mutually parallel and separated by a narrow intercellular cleft. Freeze-fracture replicas of the close junction reveal macular aggregations of intramembranous particles on the protoplasmic faces of the cellular membranes.

Structure of the Stigma and Style of the Avocado

1978 ◽  
Vol 26 (5) ◽  
pp. 663 ◽  
Author(s):  
M Sedgley ◽  
MS Buttrose
Keyword(s):  
Electron Microscopy ◽  
Smooth Endoplasmic Reticulum ◽  
Freeze Fracture ◽  
Persea Americana ◽  
Transmitting Tissue ◽  
Intercellular Substance ◽  
Thin Sections ◽  
Transmission Electron ◽  
Tissue Cells ◽  
Stigma Secretion

The structure of the stigma and style of the avocado (Persea americana Mill.) was investigated by light microscopy, scanning electron microscopy and transmission electron microscopy of thin sections and freeze-fracture replicas. The stigmalstyle was asymmetrical and a groove, lined with transmitting tissue, extended the whole length of the structure. Stigma papillae fringed this groove for about a third of its length. There was no clear distinction between stigma papillae and stylar transmitting tissue cells but there was a gradation of structure down the axis. The papilla cells were long with large and small vacuoles; the transmitting tissue cells had small vacuoles only. The stigma secretion and intercellular substance of the transmitting tissue contained carbohydrate and lipid. Clusters of plastids with little internal structure and electron-dense stroma were abundant in the cells of the stigma and transmitting tissue along with extensive smooth endoplasmic reticulum. Both single vesicles and multivesicular bodies were observed fusing with the plasmalemma which was abnormally rough in freeze-fracture profiles. It is suggested that the cells of the stigma and transmitting tissue have a largely secretory function and may be approaching or have reached senescence when the flower opens.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

SEM Examination of a Used Diamond Knife

1971 ◽  
Vol 29 ◽  
pp. 452-453
Author(s):  
J. Temple Black
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
High Magnification ◽  
Metallic Materials ◽  
Wide Spread ◽  
Thin Sections ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron ◽  
Diamond Knife

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Dislocations in alumina deformed by prismatic slip

1978 ◽  
Vol 36 (1) ◽  
pp. 606-607
Author(s):  
J. Cadoz ◽  
J. Castaing ◽  
J. Philibert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Compression Tests ◽  
Thin Sections ◽  
Burgers Vector ◽  
Maximum Deformation ◽  
Transmission Electron ◽  
Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

Cryomicroscopy of multiphase latices

1991 ◽  
Vol 49 ◽  
pp. 1060-1061
Author(s):  
O. L. Shaffer ◽  
M.S. El-Aasser ◽  
C. L. Zhao ◽  
M. A. Winnik ◽  
R. R. Shivers
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Freeze Fracture ◽  
Particle Morphology ◽  
Second Stage ◽  
Transmission Electron ◽  
Important Approach ◽  
Carbon Coated ◽  
Preparation Techniques

Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.

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