The ultrastructure of chylomicra and of the particles in an artificial fat emulsion

1968 ◽  
Vol 169 (1015) ◽  
pp. 147-152 ◽  
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Electron Microscope ◽  
Olive Oil ◽  
Sodium Citrate ◽  
Corn Oil ◽  
Dense Material ◽  
Fat Emulsion ◽  
Electron Dense Material ◽  
Fresh State

Chylomicra collected from the cannulated thoracic duct of rats fed corn oil or olive oil, and particles of an artificial fat emulsion (Intralipid), were examined with the electron microscope after osmium fixation and Epon embedding. In section, corn oil chylomicra and Intralipid particles show a pale core and an electrondense surface layer; these two zones are thought to represent the triglyceride and phospholipid components respectively. The surface layer measures 50 to 100 Å in width when sectioned transversely. It shows minute interruptions and may be laminated in focal areas. Corn oil chylomicra fixed after storage in a solution of sodium citrate for several days do not differ morphologically from those fixed in the fresh state. In section, olive oil chylomicra show a paler core and a less well-defined surface layer. When fixed in the fresh state, the more electron-dense material is located just beneath the surface of the chylomicron; after storage in citrate the electron-dense material is scattered more peripherally. The findings are discussed in relation to the composition of chylomicra and the changes which the lipids undergo during processing for electron microscopy.

Visualization of changes in ciliary tip configuration caused by sliding displacement of microtubules in macrocilia of the ctenophore Beroe

1985 ◽  
Vol 79 (1) ◽  
pp. 161-179 ◽  
Author(s):  
S.L. Tamm ◽  
S. Tamm
Keyword(s):  
Electron Microscopy ◽  
Dense Material ◽  
Bend Angle ◽  
Two Dimensional ◽  
Electron Dense Material ◽  
Central Pair ◽  
Rest Position ◽  
Recovery Stroke ◽  
Dimensional Models ◽  
As If

Macrocilia from the lips of the ctenophore Beroe consist of multiple rows of ciliary axonemes surrounded by a common membrane, with a giant capping structure at the tip. The cap is formed by extensions of the A and central-pair microtubules, which are bound together by electron-dense material into a pointed projection about 1.5 micron long. The tip undergoes visible changes in configuration during the beat cycle of macrocilia. In the rest position at the end of the effective stroke (+30 degrees total bend angle), there is no displacement between the tips of the axonemes, and the capping structure points straight into the stomach cavity. In the sigmoid arrest position at the end of the recovery stroke (−60 degrees total bend angle), the tip of the macrocilium is hook-shaped and points toward the stomach in the direction of the subsequent effective stroke. This change in tip configuration is caused by sliding displacement of microtubules that are bound together at their distal ends. Electron microscopy and two-dimensional models show that the singlet microtubule cap acts as if it were hinged to the ends of the axonemes and tilted to absorb the microtubule displacement that occurs during the recovery stroke. The straight and hooked shapes of the tip are thought to help the ctenophore ingest prey.

Electron Microscope Investigation of PVD Coated Aluminium Alloy Surface Layer

2012 ◽  
Vol 186 ◽  
pp. 192-197 ◽  
Author(s):  
Tomasz Tański ◽  
Krzysztof Labisz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Electron Microscope ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Wear Resistant ◽  
Electron Microscope Investigation ◽  
Microscope Investigation ◽  
Transmission Electron

The purpose of this work is electron microscope investigation of the Ti/TiCN/TiAlN and Cr/CrN/CrN coatings deposited by PVD process. The investigations were performed using scanning and transmission electron microscopy for the microstructure determination. By mind of the transmission electron microscopy the high resolution and phase determination was possible to obtain. The morphology was studied as well the lattice parameters for the layer matrix and substrate phase identification using diffraction methods was applied. After the coating of the aluminium alloys AlSi9Cu and AlSi9Cu4 with the selected coatings there are crystallites detected with the size of several tenth of diameter. The investigated samples were examined metallographically using electron microscope with different image techniques, also EDS microanalysis and electron diffraction was made. As an implication for the practice a new layer sequence can be possible to develop, based on PVD technique. Some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction. The originality and value of this combination of TEM investigation for PVD deposited surface lasers on aluminium alloys makes the investigation very attractive for automotive and other industry branches. Some practical implications and employment of the surface treatment technology for elements, made from tool materials, with the PVD and CVD methods, to obtain the high wear resistant coatings, makes it possible to improve the properties of these materials by – among others – decreasing for example their friction coefficient, microhardness increase, improvement of the tribological contact conditions in practical use. One original value is it also to applied the PVD method on a common material like aluminium alloy. The double layer coatings worked out In the PVD process on the Al0Si-Cu alloys substrate hale the following configuration of the layers: bottom layer/gradient layer/wear resistant hard surface layer.

Spermiogenesis and spermatozoon of the tapeworm Parabothriocephalus gracilis (Bothriocephalidea): Ultrastructural and cytochemical studies

2010 ◽  
Vol 55 (1) ◽  
Author(s):  
Lenka Šípková ◽  
Céline Levron ◽  
Mark Freeman ◽  
Tomáš Scholz
Keyword(s):  
Electron Microscopy ◽  
Anterior Extremity ◽  
Mature Spermatozoon ◽  
Dense Material ◽  
Apical Region ◽  
Cortical Microtubules ◽  
Electron Dense Material ◽  
Dense Granules ◽  
Cytoplasmic Extension ◽  
Transmission Electron

AbstractSpermiogenesis and spermatozoon ultrastructure of the tapeworm Parabothriocephalus gracilis were described using transmission electron microscopy (TEM). Spermiogenesis is characterized by the formation of a zone of differentiation with two centrioles associated with striated rootlets, and an intercentriolar body between them. The two flagella undergo a rotation of 90° until they become parallel to the median cytoplasmic extension with which they fuse. Electron-dense material is present in the apical region of the zone of differentiation in the early stages of spermiogenesis. This electron-dense material is characteristic for the orders Bothriocephalidea and Diphyllobothriidea. The mature spermatozoon contains two axonemes of the 9 + ‘1’ trepaxonematan pattern, nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the spermatozoon exhibits a single helical electron-dense crested body 130 nm thick. One of the most interesting features is the presence of a ring of cortical microtubules surrounding the axoneme. This character has been reported only for species of the order Bothriocephalidea and may be unique in this cestode group.

The distribution of condensed defect structures formed in annealed boron-implanted silicon

1969 ◽  
Vol 311 (1504) ◽  
pp. 75-78 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Electron Beam ◽  
Electron Microscope ◽  
Turbulent Jet ◽  
Doping Profile ◽  
Defect Structures ◽  
Transmission Electron ◽  
Boron Ions

Silicon has been implanted with between 10 14 and 10 16 boron ions/cm 2 at energies of 25, 50, 75 and 100 keV; it has also been annealed at temperatures of between 873 and 1073 °K when the implanted boron ions occupy substitutional sites and form a ‘doped’ surface layer in which the doping profile can be accurately controlled, a desirable property in the manufacture of solid state circuits and devices (Large & Bicknell 1967). The implanted layers have been examined by both electron microscopy and electron diffraction before, during and after annealing to study the changes in crystal structures involved. For transmission electron microscope studies the silicon must be thinned to provide areas less than 1 p m in thickness, otherwise the electron beam is entirely absorbed within the specimen. It has been found that a modified form of jet etching using a turbulent jet enables large areas suitable for transmission electron microscopy to be easily produced from all types of specimens, both annealed and unannealed. Although specimens have been prepared and implanted with boron ions of different energies and doses the results discussed, which are typical of the range covered, are those obtained from silicon implanted with single energy 50 keV boron ions with a dose of 2 x 10 15 ions/cm 2 .

Studies withBrugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species

1976 ◽  
Vol 50 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Rosemary Rogers ◽  
D. S. Ellis ◽  
D. A. Denham
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Uterine Wall ◽  
Dense Material ◽  
Intrauterine Development ◽  
Brugia Pahangi ◽  
Electron Dense Material ◽  
Large Numbers ◽  
Egg Shells ◽  
Egg Shell

ABSTRACTThe intrauterine development ofBrugia pahangiembryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its Possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of theB. pahangiembryo js distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine Jumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

scholarly journals ELECTRON MICROSCOPY OF BASOPHILIC STRUCTURES OF SOME INVERTEBRATE OOCYTES

1956 ◽  
Vol 2 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Lionel I. Rebhun
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Cross Sections ◽  
Dense Material ◽  
Continuous Space ◽  
Surf Clam ◽  
Surface View ◽  
Hexagonal Pattern

Highly basophilic plate-shaped regions from oocytes of the surf clam have been examined with the electron microscope. The regions are composed of flat, hollow vesicles perforated by pores arranged, in surface view, in a hexagonal pattern. Cross-sections of this structure show a periodicity consisting of loops (cross-sections of the continuous space within the vesicle) alternating with spaces partly filled with dense material (pores). These structures are shown to resemble closely, the nuclear envelope. Similarities to and differences from basophilic regions of other cells are discussed and it is suggested that the small granules of Palade (38) are represented by granules composing the walls of the annuli of the nuclear envelope and assumed to be present in the annuli of the vesicles. Because of differences in the structure of these regions from basophilic regions of other cells, the name periodic lamellae is suggested since the structures show periodically repeating substructures (annuli) in both cross-sections and surface views.

Role of M Cells and Macrophages in the Entrance of Mycobacterium paratuberculosis into Domes of Ileal Peyer's Patches in Calves

1988 ◽  
Vol 25 (2) ◽  
pp. 131-137 ◽  
Author(s):  
E. Momotani ◽  
D. L. Whipple ◽  
A. B. Thiermann ◽  
N. F. Cheville
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Light And Electron Microscopy ◽  
Peyer's Patches ◽  
Dense Material ◽  
M Cells ◽  
Mycobacterium Paratuberculosis ◽  
Electron Dense Material ◽  
Acid Fast Bacilli

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti- M. paratuberculosis bovine scrum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

STRUCTURE OF CHROMOSOMES VISUALIZED BY SCANNING ELECTRON MICROSCOPY

1971 ◽  
Vol 13 (4) ◽  
pp. 690-696 ◽  
Author(s):  
C. K. Yu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Rough Surface ◽  
Sodium Citrate ◽  
Chinese Hamster ◽  
Citrate Solution ◽  
Metaphase Chromosomes ◽  
Scanning Electron

Isolated metaphase chromosomes of Chinese hamster observed under the scanning electron microscope appear to have a distinct rough surface composed of chromonemata. The chromonema is a fine filament coated with nucleoprotein, which can be easily removed by hypotonic sodium citrate solution. The centromere, a narrowed, tight portion of the chromosome, is also multistranded. No membrane has been seen in metaphase chromosomes.

Selective Staining of Cortical Granules and Golgi Cisternae in Arbacia Punctulata

1969 ◽  
Vol 27 ◽  
pp. 286-287
Author(s):  
Arya K. Bal ◽  
Gilles H. Cousineau
Keyword(s):  
Electron Microscopy ◽  
Light Microscope ◽  
Phosphotungstic Acid ◽  
Dense Material ◽  
Cortical Granules ◽  
Light Microscope Level ◽  
Electron Dense Material ◽  
Selective Staining ◽  
Arbacia Punctulata ◽  
Staining Techniques

Cyto-chemical staining techniques at the light microscope level have revealed the presence of mucopolysaccharides and proteins in the cortical granules of Eichinoderm eggs. In routine electron microscopy preparation the cortical granules appear to have two morphologically distinct components - an electron dense inner component (dark bodies) surrounded by a less-electron dense material. In the present investigation it has been made possible to stain the dense inner material selectively with Phosphotungstic acid (PTA) in non-osmicated aldehyde fixed oocytes and eggs of Arbacia punctulata.

The development of the tegument and cercomer of the polycephalic larvae (cercoscolices) ofParicterotaenia paradoxa(Rudolphi, 1802) (Cestoda: Dilepididae) at the ultrastructural level

Parasitology ◽  
1984 ◽  
Vol 88 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Barbara M. MacKinnon ◽  
M. D. B. Burt
Keyword(s):  
Electron Microscopy ◽  
Developmental Stage ◽  
Cyst Wall ◽  
Proximal Part ◽  
Ultrastructural Level ◽  
Dense Material ◽  
Follicular Cells ◽  
Electron Dense Material ◽  
Inner Surface ◽  
Distal Surface

SUMMARYThe development of the tegument and cercomer ofParicterotaenia paradoxapolycephalic larvae was examined using electron microscopy. Larvae are formed by budding from the inner surface of the tegument of the degenerating hexacanth embryo. A new secondary tegument formed around the larvae is probably produced from the original hexacanth sub-tegumental cells. Microvilli covering the surface of young larvae are converted directly into microtriches, as the larvae develop, by addition of electron-dense material to the proximal part of the microvillus. Remnants of the original microvillus are visible at the distal surface of each new microthrix, but they eventually degenerate. The cercomer homologue is represented by scattered follicular cells, bearing microvilli, lying just within the containing cyst wall. The continuity of tegumentary tissue from one developmental stage to the next is discussed.

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