scholarly journals From cells to chiffon: Reminiscence of an electron microscopist

2006 ◽  
Vol 28 (6) ◽  
pp. 19-20
Author(s):  
Eve Reaven
Keyword(s):  
Electron Microscope ◽  
Golgi Body ◽  
Unusual Structure ◽  
Electron Microscopist

For a scientist, using the electron microscope can be a life-altering experience. One sits in the dark, usually alone, looking for answers to particular puzzles. Where is this immuno-tagged protein located? Why is it in this place, in this cell, in this particular site? Wait a minute! What is this unusual structure? Why does it have this strange shape? What is this density inside? Why does it seem to interact with the Golgi body?

Fine Structure of Interdental Cells in the Mouse Cochlea

1970 ◽  
Vol 28 ◽  
pp. 140-141
Author(s):  
Roberta M. Bruck
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Young Adult ◽  
Uranyl Acetate ◽  
Ground Substance ◽  
Tectorial Membrane ◽  
Lead Citrate ◽  
Unusual Structure ◽  
Thin Sections ◽  
Collagenous Fibers

An unusual structure in the cochlea is the spiral limbus; this periosteal tissue consists of stellate fibroblasts and collagenous fibers embedded in a translucent ground substance. The collagenous fibers are arranged in vertical columns (the auditory teeth of Haschke). Between the auditory teeth are interdental furrows in which the interdental cells are situated. These epithelial cells supposedly secrete the tectorial membrane.The fine structure of interdental cells in the rat was reported by Iurato (1962). Since the mouse appears to be different, a description of the fine structure of mouse interdental cells' is presented. Young adult C57BL/6J mice were perfused intervascularly with 1% paraformaldehyde/ 1.25% glutaraldehyde in .1M phosphate buffer (pH7.2-7.4). Intact cochlea were decalcified in .1M EDTA by the method of Baird (1967), postosmicated, dehydrated, and embedded in Araldite. Thin sections stained with uranyl acetate and lead citrate were examined in a Phillips EM-200 electron microscope.

A program for simulation of changes in diffraction patterns with crystal rotations

1990 ◽  
Vol 48 (1) ◽  
pp. 544-545
Author(s):  
F.C. Mijlhoff ◽  
H.W. Zandbergenl
Keyword(s):  
Electron Microscope ◽  
Reciprocal Lattice ◽  
Extensive Training ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Electron Microscopist

Orientation of crystals for HREM is done in diffraction mode. To do this efficiently thorough knowledge of the electron microscope and the reciprocal lattice of the investigated material is essential. With respect to the electron microscope extensive training is required to obtain the ability to tilt a crystal in the desired orientation. Familiarity with the reciprocal lattice of the investigated materials has to be obtained by tilt experiments on a relatively large number of crystals in the electron microscope. Even for experienced electron microscopists this can be very time consuming.In order to be able to practice tilt experiments without using the electron microscope, a program to simulate the electron microscope in diffraction mode was developed. The inexperienced electron microscopist may use the program to practice tilting of crystals. The experienced microscopist can use the program to familiarize with the reciprocal lattice of materials, which have not been studied by him before.

scholarly journals ELECTRON MICROSCOPE STUDIES ON THE DICTYOSOMES AND ACROBLASTS IN THE MALE GERM CELLS OF THE CRICKET

1956 ◽  
Vol 2 (4) ◽  
pp. 123-128 ◽  
Author(s):  
H. W. Beams ◽  
T. N. Tahmisian ◽  
R. L. Devine ◽  
Everett Anderson
Keyword(s):  
Electron Microscope ◽  
Golgi Apparatus ◽  
Electron Micrographs ◽  
Germ Cells ◽  
Light Microscope ◽  
Golgi Body ◽  
Duplex Structure ◽  
Male Germ Cells ◽  
Secondary Spermatocyte ◽  
A Chain

The dictyosome (Golgi body) in the secondary spermatocyte of the cricket appears in electron micrographs as a duplex structure composed of (a) a group of parallel double-membraned lamellae and (b) a group of associated vacuoles arranged along the compact lamellae in a chain-like fashion. This arrangement of ultramicroscopic structure for the dictyosomes is strikingly comparable to that described for the Golgi apparatus of vertebrates. Accordingly, the two are considered homologous structures. Associated with the duplex structure of the dictyosomes is a differentiated region composed of small vacuoles. This is thought to represent the pro-acrosome region described in light microscope preparations. In the spermatid the dictyosomes fuse, giving rise to the acroblast. Like the dictyosomes, the acroblasts are made up of double-membraned lamellae and associated vacuoles. In addition, a differentiated acrosome region is present which, in some preparations, may display the acrosome vacuole and granule. Both the dictyosomes and acroblasts are distinct from mitochondria.

scholarly journals The chronicles of coronaviruses: the electron microscope, the doughnut, and the spike

2020 ◽  
Vol 20 (2) ◽  
pp. 78-92
Author(s):  
K. Lalchhandama
Keyword(s):  
Electron Microscope ◽  
Large Measure ◽  
University Of Maryland ◽  
Infectious Bronchitis ◽  
Transmission Electron ◽  
American Model ◽  
Nobel Prize In Physics ◽  
Human Viruses ◽  
The University ◽  
Electron Microscopist

The advancement of medicine owes in large measure to a German engineer Ernst Ruska, whose invention of transmission electron microscope in 1931 won him the 1986 Nobel Prize in Physics, when it comes to infectious diseases. Encouraged by his physician brother Helmut Ruska to use the prototype instrument for the study of viruses, the course of virology was shifted to a different and unprecedented level. Virus could then be seen, identified and imaged. The University of Maryland happened to acquire an American model of transmission EM, the RCA EMU, using which the first structural study was done for the first known coronavirus (then was simply known as infectious bronchitis virus) in 1948. The virus was described as rounded bodies with filamentous projections. The magnification was not great and the resolution was poor. The study was followed by a series of studies using improved techniques and better EM spanning the next decade. An upgraded version RCA-EMU2A gave better images in 1957 and the virus was described as doughnut-like structure. Using Siemens Elmiskop, D.M. Berry and collaborators made the first high-resolution pictures in 1964. The thick envelope which gave doughnut-like appearance and filamentous projections reported before could be discerned as discrete pear-shaped projections called the spikes. These spikes form a corona-like halo around the virus, which were also seen in novel human viruses (B814 and 229E) that caused common colds. The discoverer of B814, David Tyrrell and his aid June Almeida, a magnificent electron microscopist, established that IBV, B814 and 229E were of the same kind of virus in 1967, which prompted to create the name coronavirus in 1968. This article further highlights the detail structural organisation of coronaviruses emanating from these pioneering research.

The limits of microanalytical information as set by electron-beam damage

1983 ◽  
Vol 41 ◽  
pp. 366-367
Author(s):  
M. S. Isaacson
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
General Practitioner ◽  
Radiation Damage ◽  
To Come ◽  
Main Item ◽  
Electron Microscopist ◽  
Beam Damage

The task given to me was try to address how radiation damage limits the information that we can extract from a sample in the electron microscope and to somehow i11ucidate what is known about the mechanism of the damage itself. I am afraid that the tasks are more formidable than I first realized, and I shall not (in this paper) be able to come to definitive conclusions. However, the attempt will be made to tie together various observations and bits of knowledge from different areas which may not be familiar to the general practitioner of electron microscopy.The area of radiation damage in electron microscopy tends to be somewhat descriptive. After all, it is really not the main item on the microscopist's agenda, but rather happens to be the unfortunate consequence of the act of viewing the sample. One can liken the electron microscopist to someone who is ill. It is not too important why or how the illness occurred, but rather, how to remedy it.

scholarly journals THE NUCLEOLAR CHANNEL SYSTEM OF HUMAN ENDOMETRIUM

1965 ◽  
Vol 27 (2) ◽  
pp. 293-304 ◽  
Author(s):  
John A. Terzakis
Keyword(s):  
Electron Microscope ◽  
Menstrual Cycle ◽  
Amorphous Matrix ◽  
Human Endometrium ◽  
Endometrial Cell ◽  
Unusual Structure ◽  
Channel System ◽  
Dense Granules ◽  
System A

Human endometrium taken during the early to mid-secretory portion of the menstrual cycle is studied with the electron microscope. A description of the nucleolus is given. In addition, an unusual structure within the endometrial cell nucleolus is described, consisting of amorphous matrix, 150-A dense granules, and a series of tubular channels. This structure is named the nucleolar channel system. A description is given of the geometric variability of the nucleolar channel system, its contents, and its relationship to the cytoplasm. The morphologic basis for a nucleolar-cytoplasmic interrelationship via the nucleolar channel system is described. Some of the implications of this relationship are discussed. The work of previous investigators on the nucleolar channel system is discussed.

The microanatomy of Hymenomonas lacuna sp.nov. (Haptophyceae)

1976 ◽  
Vol 56 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Richard N. Pienaar
Keyword(s):  
Electron Microscope ◽  
New Species ◽  
Single Layer ◽  
Golgi Body ◽  
San Juan ◽  
Culture Vessel ◽  
Relationship Of ◽  
The Relationship ◽  
A New Species

A new species of Hymenomonas Stein, Hymenomonas lacuna sp.nov. from San Juan Island, Washington, U.S.A. is described using light and electron microscope techniques. The cells normally occur in non-motile clumps growing on the sides of the culture vessel. Each cell has a body covering composed of a single layer of coccoliths of unusual construction and several layers of circular unmineralized rimless scales. Occasional small elliptical scales are sometimes found.The general cytology of the cells is discussed with special attention paid to the unusual pyrenoid and the role of the Golgi body in scale and coccolith production.The relationship of this species to H. roseola Stein is discussed.

scholarly journals Spermiogenesis in Lumbricus herculeus

1959 ◽  
Vol 6 (1) ◽  
pp. 45-52 ◽  
Author(s):  
J. Brontë Gatenby ◽  
A. J. Dalton
Keyword(s):  
Electron Microscope ◽  
Nuclear Membrane ◽  
Golgi Body ◽  
Original Position ◽  
Distal Margin ◽  
Lateral Border ◽  
Middle Piece ◽  
Usual Manner ◽  
Cytoplasmic Strand ◽  
Two Bodies

Small pieces of the sperm sacs of Lumbricus herculeus were fixed for 4 hours in chrome-osmium, embedded in methacrylate, sectioned with a Porter-Blum microtome, and studied with a R.C.A. EMU-2C electron microscope. Each spermatid of a group developing synchronously is attached by a cytoplasmic strand to a common nutrient protoplasmic mass. This mass contains mitochondria and yolk bodies but is anucleate. The proximal centriole, that is, the centriole nearer the nucleus, is at first associated with a small peg which becomes firmly attached to the nuclear membrane. Later these two bodies become separated during the development of the middle-piece which is differentiated in the usual manner from a nebenkern formed by the fusion of 6 or 7 mitochondria. The acrosome develops in relation to the dictyosome (Golgi body), itself composed of 8 or more individual flattened sacs and situated in the cytoplasm opposite the point of attachment of the spermatid to the nutrient mass. Soon after its formation, the acrosome becomes incorporated into a cytoplasmic appendage or acrosome carrier. The carrier moves from its original position, along the lateral border of the elongating nucleus, to the distal margin of the nucleus where the acrosome is deposited. No evidence was found of a centriole located at the point of junction between nucleus and acrosome as suggested by earlier workers.

Phase Contrast Enhancement by Single Sideband Modulation Transfer

1972 ◽  
Vol 30 ◽  
pp. 616-617
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Transfer Function ◽  
Spherical Aberration ◽  
Image Interpretation ◽  
Carbon Film ◽  
Modulation Transfer ◽  
Contrast Transfer Function ◽  
Single Sideband ◽  
Single Sideband Modulation ◽  
Electron Microscopist

Through-focal series of an empty carbon film with the corresponding optical diffractograms illustrate beautifully the contrast transfer theory of the electron microscope. This theory has gained great popularity among the electron microscope designers because it presents a means of obtaining an image quality figure for the instrument independent of the object, by using the contrast transfer function. Present objective lenses are nearly perfect in the sense that they perform close to the theoretical expectations. Paradoxically, this presents a serious problem for the biological electron microscopist who wants a faithful image of his sample at high magnification.Biological E.M. samples are weak phase objects and consequently the E.M. is in principle not able to image the object with any contrast. Due to spherical aberration and defocussing, details < 10 Å are transferred, but the oscillating nature of the transfer function causes image interpretation problems. Staining of the object to obtain contrast is very unsatisfactory and methods have been sought to image phase structures from 5 Å upward with enhanced contrast.

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