scholarly journals Pronuclei of Heliophrya erhardi Matthes during conjugation and their differential association with coated and uncoated microtubules

1980 ◽  
Vol 45 (1) ◽  
pp. 245-255
Author(s):  
H.N. Lanners
Keyword(s):  
Electron Microscopy ◽  
Dense Material ◽  
Differential Association ◽  
Electron Dense Material

Microtubules surrounding the pronuclei during conjugation of the suctorian ciliate Heliophrya erhardi can be divided into 2 distinct classes by electron microscopy. Microtubules around the stationary nucleus have a conventional appearance and presumably serve as a skeleton, anchoring that nucleus in its cytoplasmic position. Microtubules surrounding the prospective migratory nucleus are coated with electron-dense material and are in some cases associated with 7-nm filaments. These coated microtubules supposedly function to transport the migratory nucleus into the conjugation partner.

Visualization of changes in ciliary tip configuration caused by sliding displacement of microtubules in macrocilia of the ctenophore Beroe

1985 ◽  
Vol 79 (1) ◽  
pp. 161-179 ◽  
Author(s):  
S.L. Tamm ◽  
S. Tamm
Keyword(s):  
Electron Microscopy ◽  
Dense Material ◽  
Bend Angle ◽  
Two Dimensional ◽  
Electron Dense Material ◽  
Central Pair ◽  
Rest Position ◽  
Recovery Stroke ◽  
Dimensional Models ◽  
As If

Macrocilia from the lips of the ctenophore Beroe consist of multiple rows of ciliary axonemes surrounded by a common membrane, with a giant capping structure at the tip. The cap is formed by extensions of the A and central-pair microtubules, which are bound together by electron-dense material into a pointed projection about 1.5 micron long. The tip undergoes visible changes in configuration during the beat cycle of macrocilia. In the rest position at the end of the effective stroke (+30 degrees total bend angle), there is no displacement between the tips of the axonemes, and the capping structure points straight into the stomach cavity. In the sigmoid arrest position at the end of the recovery stroke (−60 degrees total bend angle), the tip of the macrocilium is hook-shaped and points toward the stomach in the direction of the subsequent effective stroke. This change in tip configuration is caused by sliding displacement of microtubules that are bound together at their distal ends. Electron microscopy and two-dimensional models show that the singlet microtubule cap acts as if it were hinged to the ends of the axonemes and tilted to absorb the microtubule displacement that occurs during the recovery stroke. The straight and hooked shapes of the tip are thought to help the ctenophore ingest prey.

Spermiogenesis and spermatozoon of the tapeworm Parabothriocephalus gracilis (Bothriocephalidea): Ultrastructural and cytochemical studies

2010 ◽  
Vol 55 (1) ◽  
Author(s):  
Lenka Šípková ◽  
Céline Levron ◽  
Mark Freeman ◽  
Tomáš Scholz
Keyword(s):  
Electron Microscopy ◽  
Anterior Extremity ◽  
Mature Spermatozoon ◽  
Dense Material ◽  
Apical Region ◽  
Cortical Microtubules ◽  
Electron Dense Material ◽  
Dense Granules ◽  
Cytoplasmic Extension ◽  
Transmission Electron

AbstractSpermiogenesis and spermatozoon ultrastructure of the tapeworm Parabothriocephalus gracilis were described using transmission electron microscopy (TEM). Spermiogenesis is characterized by the formation of a zone of differentiation with two centrioles associated with striated rootlets, and an intercentriolar body between them. The two flagella undergo a rotation of 90° until they become parallel to the median cytoplasmic extension with which they fuse. Electron-dense material is present in the apical region of the zone of differentiation in the early stages of spermiogenesis. This electron-dense material is characteristic for the orders Bothriocephalidea and Diphyllobothriidea. The mature spermatozoon contains two axonemes of the 9 + ‘1’ trepaxonematan pattern, nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the spermatozoon exhibits a single helical electron-dense crested body 130 nm thick. One of the most interesting features is the presence of a ring of cortical microtubules surrounding the axoneme. This character has been reported only for species of the order Bothriocephalidea and may be unique in this cestode group.

Studies withBrugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species

1976 ◽  
Vol 50 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Rosemary Rogers ◽  
D. S. Ellis ◽  
D. A. Denham
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Uterine Wall ◽  
Dense Material ◽  
Intrauterine Development ◽  
Brugia Pahangi ◽  
Electron Dense Material ◽  
Large Numbers ◽  
Egg Shells ◽  
Egg Shell

ABSTRACTThe intrauterine development ofBrugia pahangiembryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its Possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of theB. pahangiembryo js distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine Jumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

Role of M Cells and Macrophages in the Entrance of Mycobacterium paratuberculosis into Domes of Ileal Peyer's Patches in Calves

1988 ◽  
Vol 25 (2) ◽  
pp. 131-137 ◽  
Author(s):  
E. Momotani ◽  
D. L. Whipple ◽  
A. B. Thiermann ◽  
N. F. Cheville
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Light And Electron Microscopy ◽  
Peyer's Patches ◽  
Dense Material ◽  
M Cells ◽  
Mycobacterium Paratuberculosis ◽  
Electron Dense Material ◽  
Acid Fast Bacilli

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti- M. paratuberculosis bovine scrum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

Selective Staining of Cortical Granules and Golgi Cisternae in Arbacia Punctulata

1969 ◽  
Vol 27 ◽  
pp. 286-287
Author(s):  
Arya K. Bal ◽  
Gilles H. Cousineau
Keyword(s):  
Electron Microscopy ◽  
Light Microscope ◽  
Phosphotungstic Acid ◽  
Dense Material ◽  
Cortical Granules ◽  
Light Microscope Level ◽  
Electron Dense Material ◽  
Selective Staining ◽  
Arbacia Punctulata ◽  
Staining Techniques

Cyto-chemical staining techniques at the light microscope level have revealed the presence of mucopolysaccharides and proteins in the cortical granules of Eichinoderm eggs. In routine electron microscopy preparation the cortical granules appear to have two morphologically distinct components - an electron dense inner component (dark bodies) surrounded by a less-electron dense material. In the present investigation it has been made possible to stain the dense inner material selectively with Phosphotungstic acid (PTA) in non-osmicated aldehyde fixed oocytes and eggs of Arbacia punctulata.

The development of the tegument and cercomer of the polycephalic larvae (cercoscolices) ofParicterotaenia paradoxa(Rudolphi, 1802) (Cestoda: Dilepididae) at the ultrastructural level

Parasitology ◽  
1984 ◽  
Vol 88 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Barbara M. MacKinnon ◽  
M. D. B. Burt
Keyword(s):  
Electron Microscopy ◽  
Developmental Stage ◽  
Cyst Wall ◽  
Proximal Part ◽  
Ultrastructural Level ◽  
Dense Material ◽  
Follicular Cells ◽  
Electron Dense Material ◽  
Inner Surface ◽  
Distal Surface

SUMMARYThe development of the tegument and cercomer ofParicterotaenia paradoxapolycephalic larvae was examined using electron microscopy. Larvae are formed by budding from the inner surface of the tegument of the degenerating hexacanth embryo. A new secondary tegument formed around the larvae is probably produced from the original hexacanth sub-tegumental cells. Microvilli covering the surface of young larvae are converted directly into microtriches, as the larvae develop, by addition of electron-dense material to the proximal part of the microvillus. Remnants of the original microvillus are visible at the distal surface of each new microthrix, but they eventually degenerate. The cercomer homologue is represented by scattered follicular cells, bearing microvilli, lying just within the containing cyst wall. The continuity of tegumentary tissue from one developmental stage to the next is discussed.

scholarly journals Distribution and Form of Uranium-Containing Deposits in Chickens Treated with Uranyl Nitrate

1986 ◽  
Vol 23 (6) ◽  
pp. 706-711 ◽  
Author(s):  
H. H. Mollenhauer ◽  
R. B. Harvey ◽  
L. F. Kubena ◽  
R. E. Droleskey ◽  
R. Davis
Keyword(s):  
Electron Microscopy ◽  
Uranyl Nitrate ◽  
Post Treatment ◽  
Dense Material ◽  
Electron Dense Material ◽  
Cellular Degeneration ◽  
Collecting Ducts ◽  
Distal Tubules

The kidneys of chicks treated with uranyl nitrate were examined by electron microscopy. Most deposits of electron-dense material containing uranium were found in the lumina of distal tubules and collecting ducts of kidneys collected 12–24 hours post-treatment. Some deposits were present in extracellular spaces between adjacent cells. Only occasionally were deposits found intracellularly where they were associated with localized cellular degeneration. A generalized cellular degeneration over the whole kidney was seen 72–96 hours post-treatment, but this was not directly associated with the deposits of electron-dense material.

The ultrastructure of chylomicra and of the particles in an artificial fat emulsion

1968 ◽  
Vol 169 (1015) ◽  
pp. 147-152 ◽  
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Electron Microscope ◽  
Olive Oil ◽  
Sodium Citrate ◽  
Corn Oil ◽  
Dense Material ◽  
Fat Emulsion ◽  
Electron Dense Material ◽  
Fresh State

Chylomicra collected from the cannulated thoracic duct of rats fed corn oil or olive oil, and particles of an artificial fat emulsion (Intralipid), were examined with the electron microscope after osmium fixation and Epon embedding. In section, corn oil chylomicra and Intralipid particles show a pale core and an electrondense surface layer; these two zones are thought to represent the triglyceride and phospholipid components respectively. The surface layer measures 50 to 100 Å in width when sectioned transversely. It shows minute interruptions and may be laminated in focal areas. Corn oil chylomicra fixed after storage in a solution of sodium citrate for several days do not differ morphologically from those fixed in the fresh state. In section, olive oil chylomicra show a paler core and a less well-defined surface layer. When fixed in the fresh state, the more electron-dense material is located just beneath the surface of the chylomicron; after storage in citrate the electron-dense material is scattered more peripherally. The findings are discussed in relation to the composition of chylomicra and the changes which the lipids undergo during processing for electron microscopy.

scholarly journals Evidence for actin involvement in cardiac Z-lines and Z-line analogues.

1983 ◽  
Vol 96 (2) ◽  
pp. 435-442 ◽  
Author(s):  
M Yamaguchi ◽  
R M Robson ◽  
M H Stromer
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Muscle Fibers ◽  
Opposite Polarity ◽  
Dense Material ◽  
Heavy Meromyosin ◽  
Thin Filaments ◽  
Electron Dense Material ◽  
Before And After

Canine and feline cardiac Z-lines and Z-rods were examined by electron microscopy before and after digestion of muscle fibers with Ca2+-activated protease (CAF). Removal by CAF of electron-dense material which covers Z-lines and Z-rods exposed interdigitating longitudinal filaments (6-7 nm in diameter) apparently continuous with thin filaments of the respective I-bands. The newly exposed longitudinal filaments of CAF-treated Z-lines and of CAF-treated Z-rods bound heavy meromyosin and therefore are actin. The width of Z-lines and length of Z-rods are determined by the amount of overlap of actin filaments of opposite polarity. The oblique filaments in Z-lines and Z-rods are responsible for the perpendicular periodicity of Z-lines and Z-rods, and are attributed to alpha-actinin.

A cytological study of the development of Erysiphe graminis in its host barley, as influenced by the two fungicides ethirimol and propiconazole

1990 ◽  
Vol 68 (12) ◽  
pp. 2618-2628 ◽  
Author(s):  
Annerose Heller ◽  
Friedrich Grossmann ◽  
Burkhard Frenzel ◽  
Sigrun Hippe
Keyword(s):  
Electron Microscopy ◽  
Host Cell ◽  
Light And Electron Microscopy ◽  
Unknown Origin ◽  
Erysiphe Graminis ◽  
Dense Material ◽  
Ultrastructural Changes ◽  
Wall Thickening ◽  
Electron Dense Material ◽  
Host Parasite

Light and electron microscopy of barley epidermal cells treated with ethirimol or propiconazole and then inoculated with Erysiphe graminis f. sp. hordei showed the complex reaction of this host–parasite system to fungicides. The completely different biochemical modes of action of the two fungicides were reflected in the ultrastructural changes observed. Specific fungicidal effects could be distinguished from degenerative processes associated with senescence of untreated plants. For ethirimol, the first changes to be observed in the nucleus were blebbing of the outer nuclear membrane, invaginations into the nucleoplasm, and loss of the dark-staining material of nuclear pores. Later on, large areas of the cytoplasm were devoid of ribosomes. Moreover, electron-dense material was found in the perinuclear space and in cisternae of the endoplasmic reticulum. Round bodies, containing electron-dense material of unknown origin, appeared in the cytoplasm. Propiconazole, on the other hand, caused severe malformations of haustoria, host cell wall appositions, and wall thickening. The sheaths surrounding the haustoria were significantly enlarged, and vesicular and multivesicular bodies appeared in the extrahaustorial matrix. In later stages, degenerated haustoria were partially encapsulated by the host cell. Large, rectangular, electron-opaque structures, termed Fibrosinkörper, were observed in secondary hyphae. Both fungicides tested caused swelling of secondary hyphae. Key words: Erysiphe graminis f.sp. hordei, ethirimol, propiconazole, host–parasite system, cytology, electron microscopy.

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