Étude comparée de l'ultrastructure des stomates ouverts et fermés chez le Tradescantia virginiana

1984 ◽  
Vol 62 (7) ◽  
pp. 1505-1512 ◽  
Author(s):  
J. Couot-Gastelier ◽  
D. Laffray ◽  
P. Louguet
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Guard Cells ◽  
Cell Physiology ◽  
Effective Surface ◽  
Tradescantia Virginiana ◽  
Peripheral Reticulum ◽  
Rapid Exchange ◽  
Subsidiary Cells ◽  
Scanning Electron

Guard cells and subsidiary cells of Tradescantia virginiana L. were examined with transmission and scanning electron microscopy. No plasmodesmata occur in the walls between the guard cells and the subsidiary cells. The numerous mitochondria suggest that guard cells are very active. Numerous small vacuoles were observed in closed stomata, whereas few and large vacuoles were present in opened stomata. A specialized peripheral reticulum and some invaginations containing cytoplasm were observed in chloroplasts of opened stomata. This increase of effective surface of the membrane presumably allows a rapid exchange of substances to or from the chloroplast. This was not observed in mesophyll plastids. The structures described are discussed in relation to guard cell physiology.

Corrosion Inhibition of Zinc in KOH Solutions

2007 ◽  
Vol 23 ◽  
pp. 233-236 ◽  
Author(s):  
Alina Prună ◽  
V. Brânzoi ◽  
F. Brânzoi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Polarization Resistance ◽  
Cathodic Polarization ◽  
Effective Surface ◽  
Zinc Surface ◽  
Alkylammonium Salts ◽  
Morphology Characteristics ◽  
Potentiodynamic Method ◽  
Scanning Electron

The influence of electrolyte additions on the corrosion of zinc in aqueous solutions of KOH has been determined using electrochemical and nonelectrochemical techniques. These included anodic and cathodic polarization resistance and potentiodynamic method. The inhibitors studied included ZnO and tetra-alkylammonium bromides in different concentrations. From the data provided corrosion currents were calculated. The effectiveness of the inhibitors was compared and it was found that combinations of zinc oxide with tetra-alkylammonium salts were the most effective. Surface analysis obtained with scanning electron microscopy (SEM) revealed morphology characteristics developed at the zinc surface.

Leaf micromorphology in Poaceae subtribe Olyrinae (Bambusoideae) and its systematic implications

2019 ◽  
Vol 192 (1) ◽  
pp. 184-207 ◽  
Author(s):  
Jamile Fernandes Lima ◽  
Kelly Regina Batista Leite ◽  
Lynn G Clark ◽  
R Patricia de Oliveira
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Abaxial Surface ◽  
Generic Level ◽  
Leaf Micromorphology ◽  
Stomatal Complexes ◽  
Herbaceous Bamboos ◽  
Subsidiary Cells ◽  
Scanning Electron

Abstract We analysed the leaf epidermal surfaces of 52 species of herbaceous bamboos belonging to all 20 genera of subtribe Olyrinae (Olyreae). We used scanning electron microscopy (SEM) and light microscopy (LM) to describe their foliar microcharacters and test the taxonomic utility of these characters in the subtribe. Shape and distribution of silica bodies, presence, type and distribution of papillae on the long cells and subsidiary cells and the presence and distribution of prickles and macrohairs were found to be taxonomically informative, whereas microhairs were not useful in this group. The type of papillae on the abaxial surface had a robust taxonomic value mainly at the generic level, whereas the distribution of these microstructures helped to differentiate some species of Arberella, Cryptochloa, Diandrolyra, Olyra, Piresia and Sucrea. We also confirmed that in some species, papillae associated with the stomata are on the long cells and project over the stomatal complexes, whereas in other species they occur on the subsidiary cells.

scholarly journals The position and structure of the nectary in spring heath (Erica carnea L.) flowers

2012 ◽  
Vol 62 (2) ◽  
pp. 13-21 ◽  
Author(s):  
Elżbieta Weryszko-Chmielewska ◽  
Mirosław Chwil ◽  
Marek Wróbel
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Guard Cells ◽  
Small Degree ◽  
Nectar Secretion ◽  
Ecological Traits ◽  
Anomocytic Stomata ◽  
Pore Opening ◽  
Floral Nectaries ◽  
Scanning Electron

Ecological traits of <i>Erica carnea</i> L. flowers and the morphology of floral nectaries were investigated using stereoscopic, light and scanning electron microscopy. The nectary in the flowers of <i>Erica carnea</i> is located in the basal part of the ovary. It represents the gynoecial nectary type. It has the form of a yellow, ribbed ring with eight outgrowths, pointed towards the base, which alternately adjoin the stamen filaments. The height of the nectary is 400 µm and its thickness 200 - 250 µm. The parenchyma of the nectary is composed of 6 - 8 layers. Nectar secretion occurs through anomocytic stomata with a diameter of 17 µm. Guard cells are only found on the outgrowths of the nectary and they are situated most frequently at the level of other epidermal cells. During nectar secretion, a small degree of pore opening was observed. In the flowers of <i>Erica carnea</i>, secondary nectar presentation was found, with the nectar accumulating at the base of the fused corolla.

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

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).

Spontaneous Cataract in Nude Athymic Mice

1977 ◽  
Vol 35 ◽  
pp. 512-513
Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nude Mouse ◽  
Cellular Immunity ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Athymic Mice ◽  
Transmission Microscopy ◽  
Mouse Lens ◽  
Scanning Electron

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

Microbulldozing and Microchiseling

1969 ◽  
Vol 27 ◽  
pp. 134-135
Author(s):  
J.N. Ramsey ◽  
D.P. Cameron ◽  
F.W. Schneider
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Handling ◽  
Microprobe Analysis ◽  
Foreign Matter ◽  
Specific Location ◽  
Potential Problems ◽  
Knoop Indenter ◽  
Scanning Electron ◽  
Microhardness Tester

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.

A New Image Processing Technique for STEM

1974 ◽  
Vol 32 ◽  
pp. 432-433
Author(s):  
Yasushi Kokubo ◽  
Hirotami Koike ◽  
Teruo Someya
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Scanning Electron Microscopy ◽  
Elastic Scattering ◽  
Field Emission ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Energy Analyzer ◽  
Scanning Microscope ◽  
Scanning Electron

One of the advantages of scanning electron microscopy is the capability for processing the image contrast, i.e., the image processing technique. Crewe et al were the first to apply this technique to a field emission scanning microscope and show images of individual atoms. They obtained a contrast which depended exclusively on the atomic numbers of specimen elements (Zcontrast), by displaying the images treated with the intensity ratio of elastically scattered to inelastically scattered electrons. The elastic scattering electrons were extracted by a solid detector and inelastic scattering electrons by an energy analyzer. We noted, however, that there is a possibility of the same contrast being obtained only by using an annular-type solid detector consisting of multiple concentric detector elements.

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