scholarly journals THE FIBROUS STRUCTURE OF THE NERVE AXON IN RELATION TO THE LOCALIZATION OF "NEUROTUBULES"

1950 ◽  
Vol 91 (5) ◽  
pp. 499-504 ◽  
Author(s):  
Francis O. Schmitt ◽  
Betty B. Geren
Keyword(s):  
Electron Microscope ◽  
Connective Tissue ◽  
Fibrous Structure ◽  
Thin Sections ◽  
Present Evidence ◽  
Nerve Axon ◽  
Connective Tissue Sheath ◽  
Formalin Fixed

In squid, frog, rat, and human nerves examined in thin sections with the electron microscope the axon contains, in addition to certain other particulates, characteristic filaments. These filaments have diameters ranging from about 100 to 200 Å and have indefinite length. They frequently have a nodose appearance due to the presence of discontinuities sometimes fairly regularly spaced along the filaments. This structure differs unmistakably from that of the dense-edged fibrils called "neurotubules" and it is clear that the latter are not axonic constituents. Though dense-edged fibrils can readily be demonstrated in fragmented formalin-fixed nerve preparations, they are seldom observed in thin sections. When such structures were seen in these experiments they were located in the connective tissue sheath. The present evidence offers no support for the view that "neurotubules" are structural entities of normal intact nerves.

The Connective-Tissue Sheath of the Nervous System of Locusta migratoria: an Electron Microscope Study

1961 ◽  
Vol s3-102 (60) ◽  
pp. 463-467
Author(s):  
DOREEN E. ASHHURST ◽  
J. A. CHAPMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Electron Microscope ◽  
Connective Tissue ◽  
Electron Microscope Study ◽  
Locusta Migratoria ◽  
Inner Surface ◽  
Connective Tissue Sheath ◽  
Cellular Layer ◽  
Sheath Cells

The sheath is composed of an outer non-cellular layer, the neural lamella, and an inner layer of sheath cells. The neural lamella possesses a large number of collagen fibrils arranged in layers with differing orientations. The sheath cells are flattened on the inner surface of the lamella and the cytoplasm contains lipochondria, mitochondria, and small amounts of endoplasmic reticulum.

The Fine Structure of Epithelium and Mesogloea in a Sea Anemone

1960 ◽  
Vol s3-101 (56) ◽  
pp. 481-485
Author(s):  
E. J. BATHAM
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Sea Anemone ◽  
Fibrous Structure ◽  
Epithelial Surface ◽  
Thin Sections ◽  
The Common

Ultra-thin sections of mesenteries of a sea anemone provisionally referred to Metridium canum have been examined in the electron microscope. The flagella show the common 9:2 fibrous structure, the peripheral fibres fusing basally and appearing to run through continuously to basal corpuscle and banded rootlet. Arising from the epithelial surface, as well as flagella, are numerous palisade processes, some radiating from flagella bases. These extensive processes show internal fibrous structure. Mesogloeal fibres show strong banding, with a period of about 42 to 46 mµ.

Electron-microscope observations on cell nuclei in various tissues of a teleost fish: the nucleolus-associated monolayer of chromatin structural units

1976 ◽  
Vol 21 (2) ◽  
pp. 315-327
Author(s):  
H.G. Davies ◽  
M.E. Haynes
Keyword(s):  
Electron Microscope ◽  
Connective Tissue ◽  
Nuclear Envelope ◽  
Teleost Fish ◽  
Base Sequence ◽  
Cell Nuclei ◽  
Structural Units ◽  
Thin Sections ◽  
Chromatin Structural ◽  
In Cells

Observations on stain uptake by thin sections through condensed interphase chromosomes in cells from epithelial and muscle tissue in kidney and intestine, and also in fibroblasts, show a distribution into DNA-rich and DNA-poor phases similar to that already described in cells from the connective tissue blood. In all the nuclei the nucleolus, when adjacent to the nuclear envelope, is separated from the inner membrane by a monolayer of chromatin structural units, similar to the monolayer enclosed on both sides by nuclear envelope, previously described in a wide variety of organisms. The data provide further support for the hypothesis that the condensed interphase chromosomes in eukaryotes are characterized by essentially similar structural units folded to form similar patterns. This hypothesis, regarding the higher order units, is consistent with data of others which show that histones and DNA fold to form similar repeating subunits in chromatin, irrespective of the base sequence in the DNA and the origin of the histones.

Unusual Intranuclear Structures in Chick Sympathetic Neurons

1967 ◽  
Vol 25 ◽  
pp. 188-189
Author(s):  
E. B. Masurovsky ◽  
H. H. Benitez ◽  
M. R. Murray
Keyword(s):  
Electron Microscope ◽  
Sympathetic Neurons ◽  
Uranyl Acetate ◽  
Sympathetic Ganglia ◽  
Lead Citrate ◽  
Thin Sections ◽  
Cns Neurons ◽  
Mammalian Cns

Recent light- and electron microscope studies concerned with the effects of D2O on the development of chick sympathetic ganglia in long-term, organized culture revealed the presence of rod-like fibrillar formations, and associated granulofibrillar bodies, in the nuclei of control and deuterated neurons. Similar fibrillar formations have been reported in the nuclei of certain mammalian CNS neurons; however, related granulofibrillar bodies have not been previously described. Both kinds of intranuclear structures are observed in cultures fixed either in veronal acetate-buffered 2%OsO4 (pH 7. 4), or in 3.5% glutaraldehyde followed by post-osmication. Thin sections from such Epon-embedded cultures were stained with ethanolic uranyl acetate and basic lead citrate for viewing in the electron microscope.

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.

SEM Examination of a Used Diamond Knife

1971 ◽  
Vol 29 ◽  
pp. 452-453
Author(s):  
J. Temple Black
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
High Magnification ◽  
Metallic Materials ◽  
Wide Spread ◽  
Thin Sections ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron ◽  
Diamond Knife

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.

Ultrastructure of Testicular Spermatozoon of the Fish Oreochromis Niloticus

1988 ◽  
Vol 46 ◽  
pp. 278-279
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Electron Microscope ◽  
Oreochromis Niloticus ◽  
Osmium Tetroxide ◽  
Sperm Cells ◽  
Adult Fish ◽  
Testicular Sperm ◽  
Thin Sections ◽  
Important Fish ◽  
Testicular Spermatozoon ◽  
Diamond Knife

Tilapia, Oreochromis niloticus, is an economically important fish in Saudi Arabia. Elucidation of reproductive biology of this species is necessary for successful breeding program. In this paper we describe fine structure of testicular sperm cells in O, niloticus.Testes from young adult fish were fixed in gluteraldehyde (2%) and osmium tetroxide (1%), both in cacodyl ate buffer. Specimens were processed in the conventional way for electron microscopy and thin sections of tissues (obtained by cutting the blocks with a diamond knife) were stained by ura- nyl acetate and lead citrate. These were examined in a Carl Zeiss electron microscope operated at 40 kV to 60 kV. Sperm cells were obtained from testes by squeezing them in cacodyl ate buffer. They were fixed in gluteraldehyde (2%) in the same buffer, air dried, gold coated and then examined in a Philips scanning electron microscope (SEM) operated at 25kV.The spermatozoon of O. niloticus is consisting of head, midpiece and tail (Fig. 1).

Quantitation in thin Sections Within the Electron Microscope

1976 ◽  
Vol 34 ◽  
pp. 336-337
Author(s):  
J. Edie
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Electron Scattering ◽  
Volume Density ◽  
Thin Sections ◽  
Faraday Cage ◽  
Local Mass ◽  
Physical Measurements ◽  
Mass Volume ◽  
Varying Mass

In TEM image formation, the observed contrast variations within thin sections result from differential electron scattering within microregions of varying mass thickness. It is possible to utilize these electron scattering properties to obtain objective information regarding various specimen parameters (1, 2, 3).A pragmatic, empirical approach is described which enables a microscopist to perform physical measurements of thickness of thin sections and estimates of local mass, volume, density and, possibly, molecular configurations within thin sections directly in the microscope. A Faraday cage monitors the transmitted electron beam and permits measurements of electron beam intensities.

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

Ultrastructure of the lesion induced by toxin T-514 isolated from K. humboldtiana in the alveolar region of the lung

1992 ◽  
Vol 50 (1) ◽  
pp. 640-641
Author(s):  
Julio Sepúlveda-Saavedra ◽  
Beatriz González-Corona ◽  
Víctor A. Tamez Rodríguez ◽  
Ma. Victoria Bermúdez de Rocha ◽  
Alfredo Piñeyro López
Keyword(s):  
Electron Microscope ◽  
Guinea Pig ◽  
Macaca Fascicularis ◽  
Osmium Tetroxide ◽  
Lead Citrate ◽  
Severe Damage ◽  
Thin Sections ◽  
Alveolar Region ◽  
Histopathological Findings

It has been shown in previous studies that the toxin T-514 isolated from K. humboldtiana induces severe damage to the lung in treated rodents. Histopathological findings include edema, and alveolar hemorrage. However, the ultraestructure of the lesion has not been investigated. In this study we used two species of rodents: Hamster and guinea pig, and a primate: Macaca fascicularis. Animals received different single dosis of the toxin via intraperitoneal. Control animals received only the vehicle (propylen glycol). Inmediately after spontaneous death, lung samples were fixed in Karnovsky-Ito fixative, post fixed in osmium tetroxide and embedded in epon. Thin sections were prepared with an Ultratome V LKB, stained with uranly acetate and lead citrate, and studied in an electron microscope Zeiss-EM109.

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