scholarly journals An Electron Microscope Study of Myelin Figures

1959 ◽  
Vol 5 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Walther Stoeckenius
Keyword(s):  
Molecular Structure ◽  
Electron Microscope ◽  
Fatty Acid ◽  
Human Brain ◽  
Electron Microscope Study ◽  
Striking Similarity ◽  
Fixed Tissue ◽  
Thin Sections ◽  
Tissue Sections ◽  
Myelin Figures

In the electron microscope, thin sections of OsO4-fixed myelin figures from the phospholipide fraction of human brain show a pattern of parallel dark lines with a repeating period of about 40 A. It is shown that the dark lines probably represent the reaction product of OsO4 with double bonds in the fatty acid chains, thereby marking the central portion of one bimolecular lamella. The addition of globin results in dense lines 25 to 50 A wide that cover the surface of the myelin figures. When such a figure consists of only two bimolecular leaflets of lipide covered with globin, the structure shows striking similarity to the image of cell membranes in fixed tissue sections. A hypothetical schema is given of the molecular structure of the figure, and the distribution of OsO4 in it.

scholarly journals REDUCTION OF HEATING ARTIFACTS IN THIN SECTIONS EXAMINED IN THE ELECTRON MICROSCOPE

1957 ◽  
Vol 3 (6) ◽  
pp. 1017-1022 ◽  
Author(s):  
Michael L. Watson
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Melting ◽  
High Melting Point ◽  
Tissue Mass ◽  
Thin Sections ◽  
Tissue Sections ◽  
Reduce Surface Tension ◽  
Substrate Film ◽  
General Appearance

Certain phenomena affecting contrast obtained from tissue sections with the electron microscope have been investigated and a technique is described for reducing destruction by the electron beam of fine details in sections. It has been concluded that loss of embedding material is slightly higher at exposed surfaces of sections than it is at surfaces covered by substrate film. Covering of both surfaces of sections with thin films of formvar, collodion, or carbon materially improves the general appearance, reduces distortion, and sometimes reduces loss of tissue mass from the section as result of exposure to the electron beam. This improvement is considered to result from the relatively high melting-point of the covering films which serve to eliminate or reduce surface-tension or other forces operating in methacrylate softened by the electron beam.

AN ELECTRON MICROSCOPE STUDY OF THIN SECTIONS OF HAEMOPHILUS VAGINALIS (GARDNER AND DUKES) AND SOME POSSIBLY RELATED SPECIES

1966 ◽  
Vol 12 (6) ◽  
pp. 1125-1136 ◽  
Author(s):  
Alice Reyn ◽  
A. Birch-Andersen ◽  
S. P. Lapage
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Lactobacillus Acidophilus ◽  
Related Species ◽  
Electron Microscope Study ◽  
Similar Degree ◽  
Gram Positive ◽  
Thin Sections

The line structure of Haemophilus vaginalis (Gardner and Dukes 1955) was compared with that of four, possibly related species (Butyribacterium rettgeri, Corynebacterium diphtheriae var. mitis, Lactobacillus acidophilus, Haemophilus influenzae) and an unrelated species, Neisseria haemolysans, which had shown a similar degree of Gram-variability as that of H. vaginalis. Although H. vaginalis was first described as a Gram-negative rod, its fine structure, particularly that of cell wall and septa, was more like that of Gram-positive organisms. Also N. haemolysans had a fine structure close to that of Gram-positive organisms, and its typical Gram-positive cell wall varied in. thickness from one cell to another.The study did not solve the problem of the classification of the so-called H. vaginalis, but the appearance of the few strains studied in the electron microscope suggests that it: should be included in Corynebacterium or Butyribacterium rather than in Lactobacillus.

scholarly journals AN ELECTRON MICROSCOPE STUDY OF THE EARLY ASSOCIATION BETWEEN TWO MAMMALIAN VIRUSES AND THEIR HOSTS

1962 ◽  
Vol 13 (2) ◽  
pp. 303-322 ◽  
Author(s):  
Samuel Dales
Keyword(s):  
Electron Microscope ◽  
Hela Cells ◽  
Electron Microscope Study ◽  
The Other ◽  
Single Particles ◽  
Thin Sections ◽  
Infectious Process ◽  
Free Particles ◽  
Whole Mount ◽  
Early Interaction

Early interaction between two animal viruses, vaccinia and adenovirus 7, which multiply readily in L strain and HeLa cells, respectively, was examined in both whole mount preparations and in thin sections. To observe the association at the surface, cells carrying adsorbed virus were swelled under controlled conditions and then "stained" with neutral phosphotungstate. Each particle of both virus types becomes attached to the cell by several capsomeres and is then ingested by phagocytosis. Within the cell, near the surface, single particles or small clumps of adenovirus are lodged within vesicles. Deeper in the cytoplasm this virus is packed in large, numerous inclusions, whereas very close to the nuclear envelope only free particles are found. Vaccinia, on the other hand, either free or in vesicles, is always found in the cytoplasm, at some distance from the nucleus (11). Adsorption and intracellular disposition of these two viruses is discussed in relation to the infectious process.

scholarly journals An Electron Microscope Study of the Contractile Vacuole in Tokophrya infusionum

1958 ◽  
Vol 4 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Maria A. Rudzinska
Keyword(s):  
Electron Microscope ◽  
Blood Cells ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Vacuolar Membrane ◽  
Contractile Vacuole ◽  
Thin Sections ◽  
Mode Of Operation ◽  
Contractile Vacuoles ◽  
Elaborate Structure

Contractile vacuoles are organelles that collect fluid from the cytoplasm and expel it to the outside. After each discharge (systole), they appear again and expand (diastole). They are widely distributed among Protozoa, and have been found also in some fresh water algae, sponges, and recently in some blood cells of the frog, guinea pig, and man. In spite of the extensive work on the contractile vacuole, very little is known concerning its mode of operation. An electron microscope study of a suctorian Tokophrya infusionum provided an opportunity to study thin sections of contractile vacuoles, and in these some structures were found which could be part of a mechanism for the systolic and diastolic motions the organelle displays. In Tokophrya, as in Suctoria and Ciliata in general, the contractile vacuole has a permanent canal connecting it with the outside. The canal appears to have a very elaborate structure and is composed of three parts: (1) a pore; (2) a channel; and (3) a narrow tubule located in a papilla protruding into the cavity of the contractile vacuole. Whereas the pore and channel have fixed dimensions and are permanently widely open, the tubule has a changeable diameter. At diastole it is so narrow (about 25 to 30 mµ in diameter) that it could be regarded as closed, while at systole it is widely open. It is assumed that the change in diameter is due to the contraction of numerous fine fibrils (about 180 A thick) which are radially disposed around the canal in form of a truncated cone, with its tip at the channel, and its base at the vacuolar membrane. It seems most probable that the broadening of the tubule results in discharge of the content of the contractile vacuole. In the vicinity of the very thin limiting vacuolar membrane, small vesicles and canaliculi of the endoplasmic reticulum, very small dense particles, and mitochondria may be found. In addition, rows of closely packed vesicles are present in this region, and in other parts of the cytoplasm. It is suggested that they might represent dictyosome-like bodies, responsible for withdrawing fluids from the cytoplasm and then conveying them to the contractile vacuole, contributing to its expansion at diastole.

scholarly journals IDENTIFICATION OF GLYCOGEN IN ELECTRON MICROGRAPHS OF THIN TISSUE SECTIONS

1960 ◽  
Vol 8 (3) ◽  
pp. 575-589 ◽  
Author(s):  
Jean Paul Revel ◽  
Leonard Napolitano ◽  
Don W. Fawcett
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Animal Species ◽  
Short Exposure ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Microscopic Appearance ◽  
Tissue Sections ◽  
Lead Hydroxide ◽  
Electron Microscopic Appearance

The electron microscopic appearance of glycogen has been studied in the organs of several animal species. Glycogen almost always appears as roughly circular granules from 150 to 400 A in diameter. The intrinsic electron density of glycogen varies from tissue to tissue; however, treatment with lead hydroxide as described by Watson deeply stains the granules. Glycogen pellets were isolated from some of the tissues studied by centrifugation. Such pellets were shown to be glycogen by chemical and histochemical criteria. When thin sections of the pellet are examined under the electron microscope they can be seen to consist of densely packed granules similar to those found in the intact tissues. Such pellets are also stained for electron microscopy by short exposure to lead hydroxide.

scholarly journals ELECTRON MICROSCOPE STUDIES ON ENZYME ACTIVITY AND THE ISOLATION OF THIOHYDANTOIN-INDUCED MYELIN FIGURES IN RAT LIVER

1965 ◽  
Vol 25 (3) ◽  
pp. 485-493 ◽  
Author(s):  
P. B. Herdson ◽  
J. P. Kaltenbach
Keyword(s):  
Electron Microscope ◽  
Rat Liver ◽  
Osmium Tetroxide ◽  
Enzymatic Reaction ◽  
Cytoplasmic Inclusions ◽  
Thin Sections ◽  
Central Fat ◽  
High Doses ◽  
Parenchymal Cells ◽  
Myelin Figures

Characteristic cytoplasmic inclusions (myelin figures), consisting of concentric multilaminar paired membranes surrounding one or more lipid bodies, were produced in rat liver parenchymal cells by incorporating high doses of an anticonvulsant agent (Bax 422Z) into the animals' diet. Enzymatic reaction product (presumably lead phosphate) was found around the central fat of these myelin figures in liver which had been fixed in glutaraldehyde, incubated in Wachstein and Meisel's medium containing adenosine triphosphate or inosine tri- or diphosphate, postosmicated, embedded in epoxy resin, and examined in the electron microscope. In an attempt to isolate myelin figures, fresh liver from medicated rats was homogenized and differentially centrifuged. Thin sections of osmium tetroxide-fixed, Epon-embedded pellets from each fraction were examined with the electron microscope. The concentric membranous whorls, which are probably derived from cisternae of the endoplasmic reticulum, broke up as the cells were disrupted and became inextricably mixed with the microsomal fraction. However, when liver previously fixed in formalin for 24 hours was homogenized, the myelin figures remained intact.

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