CYTOPLASMIC BRIDGES AND MUSCLE SYSTEMS IN SOME POLYMYARIAN NEMATODES

1966 ◽  
Vol 44 (2) ◽  
pp. 329-340 ◽  
Author(s):  
K. A. Wright
Keyword(s):  
Electron Microscope ◽  
Muscle Cell ◽  
Light Microscope ◽  
Muscular Activity ◽  
Muscle Cells ◽  
Serial Sections ◽  
Cell Systems ◽  
Hydrostatic Skeleton ◽  
Cytoplasmic Bridges ◽  
Somatic Musculature

The somatic musculature of nine genera of nematodes (Contracaecum, Toxascaris, Toxocara, Porrocaecum, Cyslidicola, Amplicaecum, Physaloptera, Thoracostoma, and Dermatoxys) was examined by means of serial sections and dissections examined with the light microscope, and, in one instance (Thoracostoma), by use of an electron microscope. Interconnections between muscle cells (cytoplasmic bridges) were demonstrated in the musculature of the polymyarian nematodes, but could not be seen in Dermatoxys, the only meromyarian nematode studied. Cytoplasmic bridges occur in greater frequency in the anterior end of the nematodes. Innervation processes of muscle cells frequently branch before they associate with the median chords. In the head end of Toxascaris, Toxocara, and Porrocaecum, muscle cells are doubly innervated, sending innervation processes to sublateral nerve cords as well as to the median hypodermal chords. Cytoplasmic bridges probably are the basis of the electrical pathways by which contraction impulses are spread from cell to cell. The complexly interconnected muscle cell systems demonstrated undoubtedly serve, along with the nematode's hydrostatic skeleton, as the mechanism by which coordinated muscular activity is achieved.

scholarly journals AN ELECTRON MICROSCOPE STUDY OF THE EMBRYOLOGY OF THE INTERCALATED DISC IN THE HEART OF THE RABBIT

1957 ◽  
Vol 3 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Alan R. Muir
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Cardiac Muscle ◽  
Microscope Study ◽  
Light Microscope ◽  
Electron Microscope Study ◽  
Muscle Cells ◽  
Intercalated Disc ◽  
Adult Cell ◽  
Embryonic Muscle

Prenatal and postnatal cardiac muscle from rabbits has been studied by electron microscopy, after osmium fixation and methacrylate embedding. The observations showed that 1. Cell membranes divide the muscle into cellular units from the youngest embryo which was studied (9½ days after coitus) until the adult state. 2. The embryonic muscle cells contain only one nucleus, whereas the adult cell may be multinucleated. 3. At all stages of development, wherever a myofibrillar axis crosses a cellular boundary, the myofilaments are interrupted by an intercalated disc. 4. With age, increase in size and complexity of the discs render them recognisable by the light microscope.

Changes in the somatic musculature of the 4th-stage larvae of Ascaris suum Goeze, 1782 (Nematoda: Ascaridoidea) developing in swine

Parasitology ◽  
1984 ◽  
Vol 88 (1) ◽  
pp. 141-151 ◽  
Author(s):  
R. T. O'Grady
Keyword(s):  
Light Microscopy ◽  
Muscle Cell ◽  
Post Infection ◽  
Ascaris Suum ◽  
Muscle Cells ◽  
The Body ◽  
Cell Length ◽  
Fourth Stage ◽  
Posterior Section ◽  
Somatic Musculature

SUMMARYFourth-stage larvae of Ascaris suum, recovered from piglets at 11–22 days post-infection (p.i.), were examined by light microscopy for changes in the somatic musculature. During this time the estimated total number of muscle cells in the body increases from approximately 600 to 21 000 cells. This non-eutelic development appears to occur by division of platymyarian muscle cells into coelomyarian cells, thereby increasing the number of muscle cells/quadrant from 5 to 85. The incompleteness of these divisions results in sarcoplasmic connections among muscle cells, and between muscle cells and nerve chords. At 11 days p.i., immediately after the 3rd moult, the variation in muscle cell length in a quadrant, with the longest cells being at the lateral chords, has been established. The average muscle cell length at this point is 0·101 mm, the longest is 0·164 mm. These values have increased to 0·365 mm and 1·122 mm, respectively, by 22 days p.i. At 18 days p.i. those cells in the posterior section of the larva are still the shortest in the body.

Anatomy and development of the somatic musculature of the nematode Ascaris

1976 ◽  
Vol 64 (3) ◽  
pp. 773-788 ◽  
Author(s):  
A. O. Stretton
Keyword(s):  
Action Potentials ◽  
Light And Electron Microscopy ◽  
Muscle Cells ◽  
Serial Sections ◽  
Cell Numbers ◽  
Striking Increase ◽  
Neuromuscular Synapses ◽  
System A ◽  
Somatic Musculature ◽  
Number Of Cells

The musculature of the nematode Ascaris has been studied by the examination of serial sections by light and electron microscopy. The muscle cells of nematodes are unusual in that they send branches to the neurones in contrast to the more usual situation in other animals where neurones send processes to the muscles. The neuromuscular synapses are made at the ends of the arms. Muscle cells receive multiple innervations and perform integration of the combined inputs. The action potentials are initiated near the ends of the arms so each arm acts as an integrative centre. It is shown that it is common for a muscle cell to have several arms, raising the possibility that each arm may integrate different combinations of neuronal inputs. In the second larval stage the total number of muscle cells is 83. The adult has approximately 5 X 10(4) muscle cells. The very striking increase in cell numbers of the musculature is not matched by a corresponding increase in the number of cells in the nervous system. A model for the way in which a small number of neurones can co-ordinate the activity of an increasing population of muscle cells is presented.

Innervation of the Abdominal Intersegmental Muscles in the Grasshopper

1971 ◽  
Vol 55 (2) ◽  
pp. 305-313
Author(s):  
N. M. TYRER
Keyword(s):  
Electron Microscope ◽  
Individual Variation ◽  
Light Microscope ◽  
Abdominal Segment ◽  
Serial Sections ◽  
Dorsal Muscle ◽  
Melanoplus Differentialis ◽  
Dorsal Nerve

1. The course of the dorsal nerve in the fourth abdominal segment of the grasshopper Melanoplus differentialis is described. 2. Unconventional techniques of making serial sections of the dorsal nerve for examination with the electron microscope are described in detail. The method permits a higher resolution than the light microscope but lower than more conventional electronmicroscope techniques. 3. It has been demonstrated that the median dorsal internal muscles are all innervated from eight axons in the dorsal nerve. 4. Although there is individual variation in the size of these axons there is some indication that they can be divided into four pairs according to their size. 5. Of the remaining 13 axons in the dorsal nerve, two supply the median external dorsal muscle and 11 are concerned with the innervation of the heart.

Selective Staining of Acid Mucopolysaccharides By Ruthenium Red

1968 ◽  
Vol 26 ◽  
pp. 38-39
Author(s):  
J. H. Luft
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Single Cells ◽  
Ruthenium Red ◽  
Collagen Fibers ◽  
Selective Staining ◽  
Pectic Substances ◽  
Solid Tissues

Ruthenium red is one of the few completely inorganic dyes used to stain tissues for light microscopy. This novelty is enhanced by ignorance regarding its staining mechanism. However, its continued usefulness in botany for demonstrating pectic substances attests to selectivity of some sort. Whether understood or not, histochemists continue to be grateful for small favors.Ruthenium red can also be used with the electron microscope. If single cells are exposed to ruthenium red solution, sufficient mass can be bound to produce observable density in the electron microscope. Generally, this effect is not useful with solid tissues because the contrast is wasted on the damaged cells at the block surface, with little dye diffusing more than 25-50 μ into the interior. Although these traces of ruthenium red which penetrate between and around cells are visible in the light microscope, they produce negligible contrast in the electron microscope. However, its presence can be amplified by a reaction with osmium tetroxide, probably catalytically, to be easily visible by EM. Now the density is clearly seen to be extracellular and closely associated with collagen fibers (Fig. 1).

Involvement of Cyclooxygenase- and Lipoxygenase-Mediated Conversion of Arachidonic Acid in Controlling Human Vascular Smooth Muscle Cell Proliferation

1990 ◽  
Vol 63 (02) ◽  
pp. 291-297 ◽  
Author(s):  
Herm-Jan M Brinkman ◽  
Marijke F van Buul-Worteiboer ◽  
Jan A van Mourik
Keyword(s):  
Cell Proliferation ◽  
Arachidonic Acid ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Muscle Cells ◽  
Smooth Muscle Cell Proliferation

SummaryWe observed that the growth of human umbilical arterysmooth muscle cells was inhibited by the phospholipase A2 inhibitors p-bromophenacylbromide and mepacrine. Thesefindings suggest that fatty acid metabolism might be integrated in the control mechanism of vascular smooth muscle cell proliferation. To identify eicosanoids possibly involved in this process, we studied both the metabolism of arachidonic acid of these cells in more detail and the effect of certain arachidonic acid metabolites on smooth muscle cells growth. We found no evidence for the conversion of arachidonic acid via the lipoxygenase pathway. In contrast, arachidonic acid was rapidly converted via the cyclooxy-genase pathway. The following metabolites were identified: prostaglandin E2 (PGE2), 6-keto-prostaglandin F1α (6-k-PGF1α), prostaglandin F2α (PGF2α), 12-hydroxyheptadecatrienoic acid (12-HHT) and 11-hydroxyeicosatetetraenoic acid (11-HETE). PGE2 was the major metabolite detected. Arachidonic acid metabolites were only found in the culture medium, not in the cell. After synthesis, 11-HETE was cleared from the culture medium. We have previously reported that PGE2 inhibits the serum-induced [3H]-thymidine incorporation of growth-arrested human umbilical artery smooth muscle cells. Here we show that also 11-HETEexerts this inhibitory property. Thus, our data suggeststhat human umbilical artery smooth muscle cells convert arachidonic acid only via the cyclooxygenase pathway. Certain metabolites produced by this pathway, including PGE2 and 11-HETE, may inhibit vascular smooth muscle cell proliferation.

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.

Marine fungi from Seychelles. I. Nimbospora effusa and Nimbospora bipolaris sp. no v. from driftwood

1985 ◽  
Vol 63 (3) ◽  
pp. 611-615 ◽  
Author(s):  
Kevin D. Hyde ◽  
E. B. Gareth Jones
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscope ◽  
Marine Fungi ◽  
Undescribed Species ◽  
Scanning Electron

Collections of filamentous marine fungi in Seychelles included Nimbospora effusa Koch and an undescribed species, Nimbospora bipolaris Hyde & Jones sp. nov. Tha latter differs from N. effusa in the size of the ascospores and in ascospore appendage morphology. Both species are illustrated by light microscope and scanning electron microscope micrographs.

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.

The structure of the Spiracles of the cattle tick, Boophilus microplus

1967 ◽  
Vol 15 (5) ◽  
pp. 941 ◽  
Author(s):  
HE Hinton
Keyword(s):  
Electron Microscope ◽  
Ambient Air ◽  
Adult Tick ◽  
Boophilus Microplus ◽  
Ixodid Ticks ◽  
Cattle Tick ◽  
Serial Sections ◽  
Peripheral Part ◽  
Gas Exchanges ◽  
Spiracular Plate

The structures of the nymphal and adult spiracles of the tick, Boophilus microplus, have been examined by means of serial sections and a stereoscan electron microscope. Contrary to the views of recent writers, the functional openings of the spiracle have been found to be holes or aeropyles in the peripheral part of the spiracular plate of the adult tick. The ostium of previous writers is shown to be the ecdysial tube, which is present only in the spiracles of adult ixodid ticks. After the nymphal-adult ecdysis, the ecdysial tube is closed. There is thus no ostium in this stage, as has been claimed by previous writers who supposed that the chief or only route for gas exchanges between the atrium of the spiracle and the ambient air was through the so-called ostium. The ecdysial process of the spiracles of ticks is shown to be basically similar to the ecdysial process of the spiracles of certain insects such as scarabaeid larvae and the larvae of some Diptera-Cyclorrhapha.

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