Asci of the Pezizales. VI. The apical apparatus of Morchella esculenta, Helvella crispa, and Rhizina undulata. General discussion

1978 ◽  
Vol 56 (24) ◽  
pp. 3069-3082 ◽  
Author(s):  
Don A. Samuelson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Present Series ◽  
Lipid Bodies ◽  
Taxonomic Significance ◽  
Taxonomic Relatedness ◽  
Morchella Esculenta ◽  
Bitunicate Ascus

Morphological, developmental, and cytochemical examinations were made with light and electron microscopy on the apical apparatuses of Morchella esculenta, Helvella crispa, and Rhizina undulata, all species with large, stipitate apothecia. Ascus tips in R. undulata were markedly thinner walled than the rest of the ascus, while those in M. esculenta and H. crispa were slightly thinner than the rest of the ascus wall. Lipid bodies were detected in developing asci of H. crispa and M. esculenta. Their unique occurrence in asci of members of the Morchellaceae and Helvellaceae may have taxonomic significance. With the electron microscope, opercula were distinguished cytochemically in all three species. In H. crispa and M. esculenta dehiscent zones were found to be restricted in the inner layer of the ascal wall. Characters of the apical apparatuses of H. crispa and M. esculenta suggest greater taxonomic relatedness between these species than with any other operculate group. The apical apparatus of R. undulata differed notably from the other species.The present series of studies has demonstrated distinct variability of the operculate ascus and its apical apparatus in morphology, cytochemistry, and development. Several major forms of the apical structures were observed. These examinations support the chemotaxonomic and cytological investigations on representatives of the Pezizales made previously by Arpin and Berthet. Outside of the Thelebolaceae, members of the Pezizales are chiefly characterized by the operculate dehiscence of their asci. Members of the Thelebolaceae eject their spores through a variety of dehiscent mechanisms. Present examinations of those representatives of the Thelebolaceae with functionally operculate apparatuses, i.e., Lasiobolus and Coprotus, support their transferrance to the Pyronemaceae. Taxa which form nonoperative opercula, i.e.,Ascozonus and Trichobolus, also show closer affinities with the Pyronemaceae than with the nonoperculate representatives of the Thelebolaceae. The nonoperculate members of the Thelebolaceae apparently do not belong in the operculate Discomycetes. The operculate ascus wall is structurally compared with the pored and bitunicate ascus walls. The terms 'bitunicate' and 'unitunicate' are redefined.

Development of 200 kV Scanning-Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 410-411
Author(s):  
H. Koike ◽  
S. Sakurai ◽  
K. Ueno ◽  
M. Watanabe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
The Other ◽  
Morphological Observation ◽  
Magnetic Domains ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Backscattered Electron ◽  
Increasing Demand

In recent years, there has been increasing demand for higher voltage SEMs, in the field of surface observation, especially that of magnetic domains, dislocations, and electron channeling patterns by backscattered electron microscopy. On the other hand, the resolution of the CTEM has now reached 1 ∼ 2Å, and several reports have recently been made on the observation of atom images, indicating that the ultimate goal of morphological observation has beem nearly achieved.

scholarly journals An Electron Microscope Study of Basophile Substances of Frozen-Dried Rat Liver

1958 ◽  
Vol 4 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Henry Finck
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Rat Liver ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Freeze Drying ◽  
Light And Electron Microscopy ◽  
Enzyme Treatment ◽  
Dense Granules ◽  
Homogeneous Matrix

Small pieces of liver from rats subjected to different dietary regimes were fixed by freeze-drying, and postfixed by in vacuo heating and denaturation with alcohol. Specimens were digested with ribo- or deoxyribonuclease, and stained with gallocyanin-chromalum, azure II, the Feulgen procedure or alcoholic platinic tetrabromide. Some specimens were reserved as controls of the effects of enzyme treatment. Stained and unstained specimens were embedded in methacrylate and examined by light and electron microscopy. Basophilic and Feulgen-positive substances, after contact with watery reagents, were found by electron microscopy to exist as small dense granules embedded in a less dense homogeneous matrix, forming the walls of submicroscopic vacuoles. These granules were absent after digestion with nucleodepolymerases. In specimens (unstained, or stained with platinic tetrabromide) which had not passed through water, the dense (basophile) substances in nuclei and cytoplasm were found to exist, not as granules, but as ill defined submicroscopic concentrates which blended imperceptibly into the homogeneous matrix of the vacuolar walls. Objections to the use of stains for improving contrast conditions in electron microscopy of tissues are discussed, and it is concluded that the reagents do not necessarily produce the observed increases in contrast by selectively stabilizing certain structures. The concept of microsomes as pre-existing distinct morphological entities in intact (unhomogenized) cells is thought to be inconsistent with the distribution of basophile substances in frozen-dried liver.

Fine Structure of the Eye of a Nudibranch Mollusc, Hermissenda Crassicornis

1967 ◽  
Vol 2 (3) ◽  
pp. 349-358
Author(s):  
R. M. EAKIN ◽  
JANE A. WESTFALL ◽  
M. J. DENNIS
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Optic Nerve ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Sensory Cells ◽  
Nerve Fibres ◽  
Supporting Cells ◽  
Small Bodies ◽  
Receptor Cells

The eye of a nudibranch, Hermissenda crassicornis, was studied by light and electron microscopy. Three kinds of cells were observed: large sensory cells, each bearing at one end an array of microvilli (rhabdomere) and at the other end an axon which leaves the eye by the optic nerve; large pigmented supporting cells; and small epithelial cells, mostly corneal. There are five sensory cells, and the same number of nerve fibres in the optic nerve. The receptor cells contain an abundance of small vesicles, 600-800 Å in diameter. The lens is a spheroidal mass of osmiophilic, finely granular material. A basal lamina and a capsule of connective tissue enclose the eye. In some animals the eye is ‘infected’ with very small bodies, 4-5 µ in diameter, thought to be symbionts.

Ultrastructure of eastern cottonwood clones susceptible or resistant to leaf rust

1987 ◽  
Vol 65 (8) ◽  
pp. 1586-1598 ◽  
Author(s):  
L. Shain ◽  
U. Järlfors
Keyword(s):  
Electron Microscopy ◽  
Leaf Rust ◽  
Light And Electron Microscopy ◽  
Infection Process ◽  
The Other ◽  
Host Cells ◽  
Eastern Cottonwood ◽  
Melampsora Medusae ◽  
Wall Appositions ◽  
Infected Cells

The infection process in four clones of eastern cottonwood susceptible or resistant to leaf rust caused by Melampsora medusae was studied by light and electron microscopy. Infection was initiated by stomatal rather than direct entry. Typical dikaryotic haustoria were observed in all clones within 1 day of inoculation. Some healthy-appearing haustoria were observed in susceptible clones throughout the duration of the study, which was terminated during the initiation of uredial production. Incompatibility was expressed differently in the two resistant clones. In clone St 75, most haustoria and invaded host cells that were observed appeared necrotic within 2 days of inoculation. Cell wall appositions appeared during this time in cells adjoining necrotic host cells. Some infected cells disintegrated within 4 days of inoculation. Affected host cells of clone St 92, on the other hand, plasmolyzed during the first 2 to 3 days after inoculation. Necrotic host cells were not observed in this clone until the 4th day after inoculation. Hyphal ramification and host plasmolysis were extensive at 6 days after inoculation.

Mouse ovarian tissue vitrification on copper electron microscope grids versus slow freezing: a comparative ultrastructural study

2015 ◽  
Vol 27 (7) ◽  
pp. 1020 ◽  
Author(s):  
Ferda Topal-Celikkan ◽  
Sinan Ozkavukcu ◽  
Deniz Balci ◽  
Sibel Serin-Kilicoglu ◽  
Esra Atabenli-Erdemli
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Cancer Therapy ◽  
Ovarian Tissue ◽  
Light And Electron Microscopy ◽  
Slow Freezing ◽  
Ovarian Tissue Cryopreservation ◽  
Control Group ◽  
Primordial Follicles ◽  
User Friendly

There are many reasons, including cancer therapy, for premature ovarian failure and infertility. Oocyte, embryo and ovarian cryopreservation are current options for fertility preservation. Ovarian tissue cryopreservation is essential in patients whose cancer therapy cannot be delayed, including prepubertal girls, and is mostly performed using slow freezing. In the present study, mouse ovarian tissues were vitrified on copper electron microscope grids (n = 18) or conventionally slow frozen (n = 18). Post-thaw tissues were examined histologically using light and electron microscopy and compared with the control group. According to light microscopy observations, antral follicles were found to be better preserved with the slow freezing technique rather than vitrification. Electron microscopy revealed swollen mitochondria in the oocyte cytoplasm, condensations in the zona pellucida, breakages in the junctions of granulosa cells and vacuolisation in the extracellular space in pathologic follicles, which were relatively more frequent, in the vitrification group after thawing. These results indicate that ovarian slow freezing is preferable than vitrification on copper electron microscope grids, especially for larger follicles. Conversely, vitrification of ovarian pieces using cooper grids is user-friendly and provided good protection for primordial follicles and stromal cells. There is a need for further studies into advanced tissue vitrification techniques and carriers.

scholarly journals Some Reflections On How Much Information la There On A Piece Of Film, On How Film Compares With CCD Cameras And What Features A Scanner Would Meed To Digitize TEM Negatives

1998 ◽  
Vol 6 (9) ◽  
pp. 18-21
Author(s):  
Alwyn Eades
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
The Other ◽  
Ccd Cameras ◽  
Know How ◽  
Transmission Electron ◽  
The World ◽  
Digital Methods

The world of electron microscopy is in a period of transition from acquiring images on film to acquiring images digitally, using CCD cameras, for example. It would be useful to knew how much information there is on a piece of film, in order to know how film compares with digital methods and to be able to make good judgements on the optimum moment to change from one technology to the other.This is an attempt to use simple arguments to estimate just how much information there is in an image exposed on film in the transmission electron microscope, the main reason for addressing this issue Is that, while many people are affected by it there seems to be little agreement on the answer.

Nucleation in silver azide: an investigation by electron microscopy and diffraction

1955 ◽  
Vol 229 (1176) ◽  
pp. 135-142 ◽  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Single Crystals ◽  
Electron Micrographs ◽  
The Other ◽  
Metallic Silver ◽  
Silver Azide ◽  
Cubic Lattice ◽  
Early Stages ◽  
Last Stage

The beam of an electron microscope has been used to decompose single crystals of silver azide into nitrogen and metallic silver. The decomposition was slow enough to allow electrondiffraction photographs and electron micrographs to be taken at various stages of the decomposition. From these observations it is possible to follow very closely the process of nucleation. The diffraction photographs show that two forms of silver result, one highly oriented and the other randomly oriented. The microscope identifies the two forms. The randomly oriented silver appears to separate at the boundaries of a substructure of the crystal. The highly oriented silver exists as discrete nuclei, of dimensions of the order 0.1 x 0.1 x 0.05p, probably formed near the surface of the silver azide crystal. The nuclei consist of normal metallic silver only at the end of the decomposition. There is no evidence for the formation in the early stages of a small speck of metallic silver which then grows. Rather, a nucleus is a region into which silver diffuses to build up a face-centred cubic lattice of parameter greater than that of normal silver, and which uses the silver positions in the silver azide lattice as the basis for this build-up. In the last stage a collapse to normal metallic silver takes place. During decomposition the size of a nucleus does not appear to change, but the density increases.

Asci of the Pezizales. I. The apical apparatus of iodine-positive species

1978 ◽  
Vol 56 (16) ◽  
pp. 1860-1875 ◽  
Author(s):  
Don A. Samuelson
Keyword(s):  
Electron Microscopy ◽  
Positive Reaction ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Reaction Site ◽  
Lower Region

Morphological, developmental, and cytochemical studies on the apical apparatuses of five species, i.e., Peziza succosa, Ascobolus crenulatus, Saccobolus depauperatus, Thecotheus pelletieri, and Iodophanus granulipolaris, were performed with light and electron microscopy. Asci of all species, except A. crenulatus, stain blue in Melzer's reagent. The site of the iodine-positive reaction is believed to be an exogenous mucilaginous coat in P. succosa, S. depauperatus, and T. pelletieri. In I. granulipolaris, the reaction site appears to be the ascal wall. The presence of an annular indentation was found in the ascal tips of all species except I. granulipolaris. A line of dehiscence was found in the lower region of the annular indentation in T. pelletieri and S. depauperatus. The development of the apical apparatuses of all species occurs during and after late ascosporogenesis. The apical apparatus of I. granulipolaris diverged significantly in morphology and cytochemistry from the other species.

Protoplasmic changes during stomatal development in Funaria

1983 ◽  
Vol 61 (10) ◽  
pp. 2515-2526 ◽  
Author(s):  
Fred D. Sack ◽  
D. J. Paolillo Jr.
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Density ◽  
Pore Formation ◽  
Light And Electron Microscopy ◽  
Polar Regions ◽  
Lipid Bodies ◽  
Stomatal Development ◽  
Funaria Hygrometrica ◽  
Parallel Arrays

Key protoplasmic features of stomatal development in Funaria hygrometrica Hedw. (Musci) were characterized using light and electron microscopy. Endoplasmic reticulum (ER) cisternae are initially rough and often arranged in parallel arrays. During pore formation, the cytoplasm becomes packed with tubular, smooth ER. Older but still functional stomata contain small amounts of primarily cisternal ER. Lipid bodies decrease in electron density when tubular ER appears. Preliminary observations indicate that two large vacuoles occupy the polar regions of open, but not closed, stomata. Intact plasmodesmata occur in developing but not mature walls. Plastid structure, microtubule distribution, and other protoplasmic features are essentially similar to those described in the stomata of other genera.

Combined Plasma-Microincineration, Electron Microscopy And Electron Probe Microanalysis For Fine Localization of Biological Mineral Substances

1973 ◽  
Vol 31 ◽  
pp. 334-335 ◽  
Author(s):  
Richard S. Thomas ◽  
Mabel I. Corlett
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Probe ◽  
Oxygen Plasma ◽  
Chemical Nature ◽  
The Other ◽  
X Ray ◽  
Transmission Electron ◽  
Mineral Substances ◽  
Fine Localization

Ash patterns produced by oxygen plasma microincineration(OPM) of thin-sectioned biological materials and examined with the transmission electron microscope (TEM) can show unambiguously the distribution of mineral substances in the specimen with resolutions down to 100 Å. The chemical nature of the mineral is not demonstrated, however. Electron-probe X-ray microanalysis (EXM), on the other hand, can determine precisely the nature of the mineral in ashgd or unashed sections but its spatial resolution is limited to 1000-10,000 A at best. Also its sensitivity of analysis on unashed specimens is limited by intolerance of the specimen to high beam intensities. Using both TEM and EXM together on ash patterns of suitable specimens can overcome their independent spatial and chemical limitations. Furthermore, use of OPM produces a highly stable mineral specimen for EXM, thereby improving sensitivity.

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