The Ultra-fine Structure of Lipid Globules in the Neurones of Helix aspersa

1958 ◽  
Vol s3-99 (46) ◽  
pp. 279-284
Author(s):  
J.T. Y. CHOU ◽  
G. A. MEEK
Keyword(s):  
Methylene Blue ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Helix Aspersa

The three kinds of lipid globules recognizable in the living neurones of Helix aspersa have been examined under the electron microscope. The globules of the kind that can be stained blue with methylene blue during life are seen in electron micrographs as spheres or spheroids, with concentric lamination, after calcium-osmium fixation. After fixation with sucrose-osmium laminated crescentic bodies are seen instead; these appear to be formed by distortion of the ‘blue’ globules. The yellow globules contain electrondense material, and sometimes appear reticular. It is possible that the yellow globules may originate by transformation of some of the ‘blue’ globules. The colourless globules generally appear as crenated objects; this appearance may be a shrinkage artifact. Apart from the mitochondria and the three kinds of lipid globules described, no other object large enough to be identified with the light microscope has been seen in the cytoplasm.

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 Structure of the Rete Mirabile in the Kidney of the Rat as Seen with the Electron Microscope

1960 ◽  
Vol 7 (1) ◽  
pp. 103-106 ◽  
Author(s):  
J. B. Longley ◽  
W. G. Banfield ◽  
D. C. Brindley
Keyword(s):  
Endothelial Cells ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Simple Diffusion ◽  
Functional Capabilities ◽  
Rete Mirabile ◽  
Peritubular Capillaries ◽  
Fenestrated Endothelium

Electron micrographs of the rete mirabile in the medulla of the rat have revealed that the endothelium of the afferent and efferent vessels are markedly different in fine structure. The venous capillaries returning blood from the papilla are lined with a fenestrated endothelium much like that in the peritubular capillaries of the kidney. The arterial capillaries delivering blood to the papilla have an unperforated lining of overlapping endothelial cells with extremely irregular tapered margins. It is pointed out that the organization of particularly the latter vessels suggests that the functional capabilities of these retia go beyond those of a simple diffusion countercurrent exchanger.

scholarly journals THE FINE STRUCTURE OF THE RAT CEREBELLUM

1964 ◽  
Vol 23 (2) ◽  
pp. 277-293 ◽  
Author(s):  
Robert M. Herndon
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Granule Cells ◽  
Cell Types ◽  
Bergmann Glia ◽  
Rat Cerebellum

This paper describes the fine structure of the granule cells, stellate neurons, astrocytes, Bergmann glia, oligodendrocytes, and microglia of the rat cerebellum after fixation by perfusion with buffered 1 per cent osmium tetroxide. Criteria are given for differentiating the various cell types, and the findings are correlated with previous light microscope and electron microscope studies of the cerebellum.

THE EMBRYOLOGY OF LYTTA VIRIDANA LE CONTE (COLEOPTERA: MELOIDAE): II. THE STRUCTURE OF THE VITELLINE MEMBRANE

1967 ◽  
Vol 45 (4) ◽  
pp. 497-503 ◽  
Author(s):  
R. G. Gerrity ◽  
J. G. Rempel ◽  
P. R. Sweeny ◽  
N. S. Church
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Light Microscope ◽  
Three Dimensional ◽  
Apparent Porosity ◽  
Vitelline Membrane ◽  
Sperm Penetration

This paper deals with the structure of the vitelline membrane of Lytta viridana as seen through the light microscope and the electron microscope. Through the light microscope, the vitelline membrane of a freshly laid egg appears to be porous. This condition persists for 15–30 min. During this time the pores become progressively smaller until the membrane becomes solid and continuous. The electron microscope reveals that the vitelline membrane of the freshly laid egg is actually composed of a three-dimensional membranous system which condenses into a homogeneous membrane after 15–30 min. The apparent porosity of the membrane as seen through the light microscope is interpreted in terms of its fine structure, and the belief is expressed that solidification of the membranous system is initiated by sperm penetration.

The distribution and fine structure of the integumentary papillae of the cercaria ofHimasthla secunda(Nicoll)

Parasitology ◽  
1970 ◽  
Vol 61 (2) ◽  
pp. 219-227 ◽  
Author(s):  
H. D. Chapman ◽  
R. A. Wilson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spatial Distribution ◽  
Fine Structure ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Silver Nitrate ◽  
Light Microscope ◽  
Transmission Electron ◽  
Scanning Electron

The distribution of the integumentary papillae of the cercaria ofHimasthla secundahas been studied by a variety of techniques. Structures stained by silver nitrate and visible under the light microscope correspond in their spatial distribution with papillae observed under the scanning electron microscope. The tegumentary papillae described with the light and scanning electron microscope are correlated with the specialized nerve endings in the tegument as seen in transmission electron microscopy. The ultrastructure of these papillae is examined by conventional transmission electron microscopy and the probability that these structures are sensory is discussed.

scholarly journals OBSERVATIONS WITH THE ELECTRON MICROSCOPE ON THE FINE STRUCTURE OF THE NUCLEI OF TWO SPHERICAL BACTERIA

1961 ◽  
Vol 9 (1) ◽  
pp. 171-181 ◽  
Author(s):  
Woutera Van Iterson ◽  
C. F. Robinow
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Growth Cycle ◽  
The Other ◽  
Low Density ◽  
Thin Sections ◽  
Dna Molecule

The nuclei of two spherical bacteria have been examined in electron micrographs of thin sections of specimens prepared by the method of Ryter and Kellenberger (1958). The nuclei appear to consist of the same fine fibers in a matrix of low density which have already been seen in many other bacteria prepared by the same procedure. They are worth a separate description because their constituent fibers are arranged in patterns of uncommon orderliness. In the nuclei of one of the two bacteria this is seen at all times, in the nuclei of the other one only at the beginning of the growth cycle. In some places the diameter of the nuclear fibers is close to that of the DNA molecule in the model of Watson and Crick (1953).

scholarly journals STUDIES ON INFLAMMATION

1961 ◽  
Vol 11 (3) ◽  
pp. 571-605 ◽  
Author(s):  
G. Majno ◽  
G. E. Palade
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Blood Vessels ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Intercellular Junctions ◽  
Supporting Evidence ◽  
Electron Microscopic ◽  
Tracer Particles

The mechanism, whereby histamine and serotonin increase the permeability of blood vessels, was studied in the rat by means of the electron microscope. The drugs were injected subcutaneously into the scrotum, whence they diffused into the underlying (striated) cremaster muscle. An intravenous injection of colloidal HgS was also given, in order to facilitate the identification of leaks by means of visible tracer particles. After intervals varying from 1 minute to 57 days the animals were killed; the cremaster was fixed, embedded in methacrylate, and examined with the electron microscope. One to 12 minutes after the injection, the blood vessels of the smallest caliber (3 to 5 micra as measured on electron micrographs) appeared intact. Numerous endothelial openings were present in blood vessels with a diameter of 7 to 8 micra or more. These gaps were 0.1 to 0.8 micra in width; portions of intercellular junctions were often present in one or both of the margins. The underlying basement membrane was morphologically intact. An accumulation of tracer particles and chylomicra against the basement membrane indicated that the latter behaved as a filter, allowing fluid to escape but retaining and concentrating suspended particulate matter of the size used. Uptake of tracer particles by endothelial vesicles was minimal. Phagocytosis by endothelial cells became more prominent at 3 hours, but as a secondary occurrence; the pericytes were actively phagocytic at all stages. At the 3-hour stage no leaks were found. The changes induced by histamine and serotonin were indistinguishable, except that the latter was more potent on a mole-to-mole basis. In control animals only small accumulations of tracer particles were found in the wall of a number of blood vessels. With regard to the pathogenesis of the endothelial leaks, the electron microscopic findings suggested that the endothelial cells become partially disconnected along the intercellular junctions. Supporting evidence was provided at the level of the light microscope, by demonstrating—in the same preparation—the leaks with appropriate tracer particles1, and the intercellular junctions by the silver nitrate method. The lipid nature of the chylomicron deposits observed in electron micrographs was also confirmed at the level of the light microscope, using cremasters fixed in formalin and stained in toto with sudan red.

The fine structure of the body wall of Polymorphus minutus (Goeze, 1782) (Acanthocephala)

Parasitology ◽  
1965 ◽  
Vol 55 (2) ◽  
pp. 357-364 ◽  
Author(s):  
D. W. T. Crompton ◽  
D. L. Lee
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Light Microscope ◽  
Body Wall ◽  
Technical Assistance ◽  
The Body ◽  
Parasitic Nematodes ◽  
Surface Layers ◽  
Longitudinal Muscles

The body wall of Polymorphus minutus has been studied with the electron microscope and the structure of the various layers has been described.The layers are the same in number as those seen with the light microscope, and pores have been found which penetrate the cuticle. Thus, the structure of the surface layers is such as would facilitate the absorption of nutrients.It has been found that the cuticle and striped layer extend over the trunk spines, a feature which increases the area of the absorptive surface of the parasite.The structure of the striped layer of the praesoma supports the theory that the praesoma body wall and lemnisci are involved in the absorption of fat.Mitochondria have been detected in the felt and radial layers of the body wall and in the circular and longitudinal muscles.The body wall of this acanthocephalan worm is entirely different from the body wall of trematodes, cestodes and parasitic nematodes.We are grateful to Dr P. Tate for helpful discussions, Dr R. J. Skaer for criticism of the manuscript and to Professor J. D. Boyd for permission to use the electron microscope in the Department of Anatomy. Thanks are also due to Mr A. J. Page for technical assistance.

The structure of the nematocyst thread and the geometry of discharge in Corynactis viridis Allman

1965 ◽  
Vol 250 (764) ◽  
pp. 131-164 ◽  
Keyword(s):  
Electron Microscope ◽  
Surface Area ◽  
Water Vapour ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Hexagonal Array ◽  
Capsule Wall ◽  
Compact Mass ◽  
Screw Surface ◽  
Flocculent Material

Electron microscope studies reveal that the undischarged nematocyst thread is not (as the light microscope image suggests) a cylinder containing a compact mass of barbs, but a screw, as first shown in the electron micrographs of Bretschneider (1949). In the process of discharge, the screw surface is converted to a cylinder without significant change in surface area. This transformation is markedly anisometric, the length of the thread increasing almost threefold, while the overall increase in diameter is less than 50 %. The screw shape of the undischarged thread is due to the presence of three helical pleats in the membrane; and discharge results in the smoothing out of these. The cavity of the thread is smaller in the undischarged condition—because of the presence of pleats—and is largely filled by the whorls of asymmetrical barbs (three to a whorl); the tips of the barbs are pressed closely together, while their spatulate bases are distributed in open hexagonal array over the pleated surface of the thread. Barbs readily become detached from the surface of the discharged thread, leaving a complex, striated scar. The discharged thread is a slightly tapering tube in holotrichous isorhizas, and the barbs show systematic changes in size and proportions with taper. Electron micrographs show that the cavity of the undischarged thread is filled with a flocculent material, as is the space between the capsule wall and the thread. This material is presumably the highly hygroscopic proteinaceous working substance responsible for the increase in volume of the capsular fluid—at least up to 200 %—on hydration. The undischarged thread and its contents, isolated under anhydrous conditions, are conspicuously hygroscopic and perform movements of elongation and rotation as water vapour is admitted to or removed from the system. The transformation of a membrane in the form of a screw surface to a cylinder, such as occurs in the discharge of the nematocyst thread, is only possible if portions of the membrane in the trough of the screw increase in area, or portions of the pleats decrease in area. The apparent constancy of the area of the thread throughout discharge suggests that both processes may occur.

The fine structure of the trunk and praesoma wall of Acanthocephalus ranae (Schrank, 1788), Lühe, 1911

Parasitology ◽  
1967 ◽  
Vol 57 (3) ◽  
pp. 475-486 ◽  
Author(s):  
R. A. Hammond
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Electron Microscope ◽  
Light Microscope ◽  
Body Wall ◽  
Technical Assistance ◽  
The Body ◽  
The Other ◽  
Fat Excretion ◽  
Research Grant

The wall of the trunk, that of the praesoma, and the lemnisci of Acanthocephalus ranae have been studied by electron microscopy. Striations visible in sections of the body wall under the light microscope do not correspond with the ‘striped layer’ revealed by the electron microscope.A new region, the ‘canal layer’, has been described. This contains canals running into the body wall from cuticular pores.Structurally the wall of the trunk and that of the praesoma are similar. The lemnisci resemble the ‘inner layer’ of the praesoma wall. However, it is suggested that the wall of the trunk differs physiologically from that of the praesoma, and from the lemnisci. The possible roles of the wall of the praesoma and the lemnisci in fat excretion or uptake have been discussed.The body wall of A. ranae has been compared with that of the other acantho-cephalans studied with the electron microscope.Grateful acknowledgement is made to D.S.I.R. (now S.R.C.) for a research grant to the Department of Zoology for the purchase of a Huxley ultramicrotome, a vacuum coating unit, and an AEI EM 6 electron microscope.I am grateful to Dr D. A. Erasmus for reading and criticizing the manuscript, and to Mr T. Davies for valuable technical assistance.

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