On the ultrastructure of the polycercus larva of Paricterotaenia paradoxa (Cestoda: Cyclophyllidea)

1974 ◽  
Vol 52 (11) ◽  
pp. 1397-1405 ◽  
Author(s):  
D. G. Crowe ◽  
M. D. B. Burt ◽  
J. S. Scott
Keyword(s):  
Electron Microscopy ◽  
Echinococcus Granulosus ◽  
Basal Lamina ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Great Similarity ◽  
Asexual Multiplication ◽  
Secretory Products ◽  
Unusual Type

Mature polycercus larvae of Paricterotaenia paradoxa were examined by light and electron microscopy. Although the larvae are of the cysticercoid type, they showed great similarity to the hydatid larvae of Echinococcus granulosus with respect to asexual multiplication and the presence of a PAS-positive layer of tissue that surrounds the larva. The microtriches were found to be of three different forms depending on their location. Two types of secretory products are described, one apparently associated with hook formation and the other apparently neurosecretory, associated with the extensive musculature. The suckers were found to be discrete organs covered by the scolex tegument and enclosed by a membrane contiguous with the basal lamina. The present findings of this unusual type of cestode larva are compared to the more normal cysticercoid and cysticercus larvae described by other workers.

Fine Structure of the Eye of a Nudibranch Mollusc, Hermissenda Crassicornis

1967 ◽  
Vol 2 (3) ◽  
pp. 349-358
Author(s):  
R. M. EAKIN ◽  
JANE A. WESTFALL ◽  
M. J. DENNIS
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Optic Nerve ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Sensory Cells ◽  
Nerve Fibres ◽  
Supporting Cells ◽  
Small Bodies ◽  
Receptor Cells

The eye of a nudibranch, Hermissenda crassicornis, was studied by light and electron microscopy. Three kinds of cells were observed: large sensory cells, each bearing at one end an array of microvilli (rhabdomere) and at the other end an axon which leaves the eye by the optic nerve; large pigmented supporting cells; and small epithelial cells, mostly corneal. There are five sensory cells, and the same number of nerve fibres in the optic nerve. The receptor cells contain an abundance of small vesicles, 600-800 Å in diameter. The lens is a spheroidal mass of osmiophilic, finely granular material. A basal lamina and a capsule of connective tissue enclose the eye. In some animals the eye is ‘infected’ with very small bodies, 4-5 µ in diameter, thought to be symbionts.

Ultrastructure of eastern cottonwood clones susceptible or resistant to leaf rust

1987 ◽  
Vol 65 (8) ◽  
pp. 1586-1598 ◽  
Author(s):  
L. Shain ◽  
U. Järlfors
Keyword(s):  
Electron Microscopy ◽  
Leaf Rust ◽  
Light And Electron Microscopy ◽  
Infection Process ◽  
The Other ◽  
Host Cells ◽  
Eastern Cottonwood ◽  
Melampsora Medusae ◽  
Wall Appositions ◽  
Infected Cells

The infection process in four clones of eastern cottonwood susceptible or resistant to leaf rust caused by Melampsora medusae was studied by light and electron microscopy. Infection was initiated by stomatal rather than direct entry. Typical dikaryotic haustoria were observed in all clones within 1 day of inoculation. Some healthy-appearing haustoria were observed in susceptible clones throughout the duration of the study, which was terminated during the initiation of uredial production. Incompatibility was expressed differently in the two resistant clones. In clone St 75, most haustoria and invaded host cells that were observed appeared necrotic within 2 days of inoculation. Cell wall appositions appeared during this time in cells adjoining necrotic host cells. Some infected cells disintegrated within 4 days of inoculation. Affected host cells of clone St 92, on the other hand, plasmolyzed during the first 2 to 3 days after inoculation. Necrotic host cells were not observed in this clone until the 4th day after inoculation. Hyphal ramification and host plasmolysis were extensive at 6 days after inoculation.

Asci of the Pezizales. I. The apical apparatus of iodine-positive species

1978 ◽  
Vol 56 (16) ◽  
pp. 1860-1875 ◽  
Author(s):  
Don A. Samuelson
Keyword(s):  
Electron Microscopy ◽  
Positive Reaction ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Reaction Site ◽  
Lower Region

Morphological, developmental, and cytochemical studies on the apical apparatuses of five species, i.e., Peziza succosa, Ascobolus crenulatus, Saccobolus depauperatus, Thecotheus pelletieri, and Iodophanus granulipolaris, were performed with light and electron microscopy. Asci of all species, except A. crenulatus, stain blue in Melzer's reagent. The site of the iodine-positive reaction is believed to be an exogenous mucilaginous coat in P. succosa, S. depauperatus, and T. pelletieri. In I. granulipolaris, the reaction site appears to be the ascal wall. The presence of an annular indentation was found in the ascal tips of all species except I. granulipolaris. A line of dehiscence was found in the lower region of the annular indentation in T. pelletieri and S. depauperatus. The development of the apical apparatuses of all species occurs during and after late ascosporogenesis. The apical apparatus of I. granulipolaris diverged significantly in morphology and cytochemistry from the other species.

Somatic mitosis in Erysiphe graminis hordei

1972 ◽  
Vol 18 (12) ◽  
pp. 1915-1922 ◽  
Author(s):  
W. E. McKeen
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Nuclear Membrane ◽  
Osmium Tetroxide ◽  
Central Body ◽  
Nuclear Division ◽  
Light And Electron Microscopy ◽  
Erysiphe Graminis ◽  
The Other ◽  
Erysiphe Graminis Hordei

Somatic nuclear division in Erysiphe graminis hordei was studied by light and electron microscopy after various fixation and staining procedures. Electron microscopy studies of alcohol – acetic acid fixed material aided in providing an understanding of nuclear division and showing the gross alterations which occurred. Light microscopy indicated that a central body was always present at a specific site on the nuclear membrane in the interphase nucleus and was connected to chromatic spherical bodies. Microtubules were preserved when a short glutaraldehyde – osmium tetroxide fixation was used. Some microtubules extend from plaque to plaque while others terminate in kinetochores. A microtubular spindle, oblique to the nuclear and mildew-cells axes formed within the nuclear membrane. Typical prophases, metaphases, anaphases, and telophases were observed. Then one set of daughter chromatids bypassed the nucleolus which persisted intranuclearly until the daughter nuclei reached their destination, and the other set of daughter chromatids moved to midpoint in the other daughter cell. A narrow corridor, which connected daughter nuclei for some time, was filled mainly with microtubules and probably was the filament which was observed in the nucleus by light microscopy during nuclear division. At least six chromosomes were present in each nucleus.

Fine structure of the pecten oculi of the common loon (Gavia immer)

1986 ◽  
Vol 64 (10) ◽  
pp. 2181-2186 ◽  
Author(s):  
C. R. Braekevelt
Keyword(s):  
Electron Microscopy ◽  
Basal Lamina ◽  
Light And Electron Microscopy ◽  
Gavia Immer ◽  
Common Loon ◽  
Luminal Surface ◽  
Pecten Oculi ◽  
The Common ◽  
Diving Bird ◽  
Region Form

The pecten oculi of a diurnally active diving bird, the common loon (Gavia immer), was studied by light and electron microscopy. In this species the pecten consists of a pleated, highly vascular, pigmented structure that is situated over the optic nerve head and projects into the vitreous chamber. Fourteen to 15 accordion folds are joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. A distinct basal lamina encloses the entire pecten. Within each fold are numerous capillaries, melanocytes, and larger blood vessels that are often difficult to differentiate as either arterioles or venules. The capillaries are surrounded by basal laminae separated from the endothelial cells by several fibrillar layers. Pericytes are often enclosed within the basal lamina. These capillaries display numerous microfolds on their luminal surface, with a slightly reduced number of processes on the abluminal border. The endothelial cell body is extremely thin and most organelles are in the paranuclear region. The melanocytes, which are most numerous in the bridge region, form an incomplete sheath around these capillaries. As in other species, the morphology of the pecten in the loon indicates a heavy involvement in the transport of materials.

Unusual macromorphology of the ductuli efferentes and epididymis of the koala (Phascolarctos cinereus)

2000 ◽  
Vol 48 (6) ◽  
pp. 681
Author(s):  
Rachel J. Gibson ◽  
Chris M. Leigh ◽  
William G. Breed
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Secretory Activity ◽  
The Other ◽  
Ciliated Cells ◽  
Phascolarctos Cinereus ◽  
Ductuli Efferentes ◽  
Sds Page ◽  
Marsupial Species ◽  
Electron Lucent

The macromorphology of the ductuli efferentes and epididymis of the koala (Phascolarctos cinereus) was investigated and found to differ from that of other marsupial species that have been described as it comprised four macroscopically distinct lobes. Light and electron microscopy of epithelium of the duct within these lobes showed that there were principal and ciliated cells lining the duct of the first lobe, indicating it to be composed of ductuli efferentes. In the other three lobes, the epithelium contained principal, basal, electron-lucent, and mitochondria-rich cells, showing that these three lobes included the epithelium of the epididymis. The height of this epithelium gradually increased along the duct (contrary to the situation in most other species that have been studied, in which a decrease occurs). Preliminary 1D-SDS PAGE observations of flushes from the caput and cauda epididymides suggested that epididymal proteins were secreted along much of the length of the duct; the greater height of the cauda epithelium may relate to the greater protein synthetic and secretory activity in this region.

scholarly journals Structural characterization of a rat acinar cell tumor.

1982 ◽  
Vol 95 (3) ◽  
pp. 727-733 ◽  
Author(s):  
V Iwanij ◽  
B E Hull ◽  
J D Jamieson
Keyword(s):  
Electron Microscopy ◽  
Tumor Cells ◽  
Basal Lamina ◽  
Acinar Cell ◽  
Light And Electron Microscopy ◽  
Freeze Fracture ◽  
Cell Tumor ◽  
Zymogen Granule ◽  
Junctional Complexes ◽  
Freeze Fracture Electron Microscopy

A transplantable acinar cell tumor of the rat pancreas has been examined by light and electron microscopy. The tumor cells, though highly cytodifferentiated and characterized by the presence of abundant rough-surfaced endoplasmic reticulum, elements of the Golgi complex, and zymogen granules, undergo mitosis in a manner similar to that seen in the developing pancreas. Cells in the parenchyma of the tumor grow as disarrayed cords and sheets, are randomly oriented with respect to each other, and do not form acinar structures. However, when in contact with the adventitial surface of blood vessels, the tumor cells palisade and form a polarized layer of cells with their zymogen granule-rich poles oriented away from the vessel lumen. Only in this area of the tumor is a basal lamina present that underlies the basal plasmalemma of the reoriented epithelial cells. Freeze-fracture electron microscopy of tumor cells in the parenchyma shows extensive disruption of tight junctions whose sealing strands are randomly distributed over the entire plasmalemma. Gap junctions are infrequent and when present are often enclosed by tight-junctional strands. Intramembrane particles are randomly distributed over the cell surface. Both the absence of basal lamina and derangement of the junctional complexes may account in part for the altered morphogenesis of this tumor.

The differentiation of mouse gonads in vitro: a light and electron microscopical study

Development ◽  
1986 ◽  
Vol 97 (1) ◽  
pp. 189-199
Author(s):  
Sarah Mackay ◽  
Robert A. Smith
Keyword(s):  
Electron Microscopy ◽  
Culture Medium ◽  
Light And Electron Microscopy ◽  
Calf Serum ◽  
Microscopical Study ◽  
Electron Microscopical Study ◽  
The Other ◽  
Foetal Calf Serum ◽  
Electron Microscopical

Indifferent urogenital complexes were excised from mouse foetuses assessed by developmental criteria as day 10·5 or 11. After 4 or 6–7 days in culture, complexes were fixed and examined by light and electron microscopy. The effect of culturing sexed complexes in mixed sex groups was investigated. The effect of the presence or absence of foetal calf serum in the culture medium was considered. No evidence of inhibition of one sex by the other was found. Ovaries developed further in cultures than testes.

The Mouse Testis as a Model for the Study of Age Related Fine Structural Changes

1975 ◽  
Vol 33 ◽  
pp. 586-587
Author(s):  
J.E. Johnson ◽  
J. Miquel
Keyword(s):  
Electron Microscopy ◽  
Sertoli Cells ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Interstitial Cells ◽  
Comparative Investigation ◽  
The Other ◽  
Vascular Perfusion ◽  
Dense Bodies ◽  
Age Related

In studying the morphology of aging cells, it is generally concluded that different changes occur in fixed postmitotic cells as compared to those cells which divide actively throughout life. The testis appears to be an excellent model for a comparative investigation of such changes, since it contains some cells which are essentially non-dividing in adulthood (Sertoli cells and interstitial cells) as well as other cells which divide continuously in mature animals (spermatogonia and spermatocytes).We have examined, by light and electron microscopy, the testes of numerous C57BL/6J mice at ages ranging from 3 to 30 months. All tissues were fixed by vascular perfusion with paraformaldehyde and glutaraldehyde mixtures in phosphate buffer.Sertoli cells (Fig. 1) and interstitial cells (Fig. 2) in aging animals contain a large number of dense bodies (presumably lipofuscin). On the other hand, dense bodies are not seen in spermatogonia, spermatocytes or spermatids (Fig. 1).

scholarly journals Micromorphology and Systematic Distribution of Pit Membrane Thickenings in Oleaceae: Tori and Pseudo-Tori

IAWA Journal ◽  
2008 ◽  
Vol 29 (4) ◽  
pp. 409-424 ◽  
Author(s):  
David Rabaey ◽  
Suzy Huysmans ◽  
Frederic Lens ◽  
Erik Smets ◽  
Steven Jansen
Keyword(s):  
Electron Microscopy ◽  
Functional Significance ◽  
New Records ◽  
Light And Electron Microscopy ◽  
Functional Adaptation ◽  
The Other ◽  
General Interest ◽  
Pit Membrane ◽  
The Family ◽  
Structural Differences

Recent studies on the functional significance of pit membranes in water conducting cells have renewed general interest in their micromorphology. At least two types of pit membrane thickenings have been described in angiosperm families, i.e. genuine tori and pseudo-tori. This study explores the distribution and morphology of pit membrane thickenings in 69 species and 23 genera within Oleaceae using light and electron microscopy. Torus-bearing pit membranes are confirmed for Osmanthus, and new records are reported for Chionanthus retusa, Picconia azorica, and P. excelsa, but not for the other species studied of Chionanthus. This infrageneric variation suggests that tori represent a plastic feature that has evolved more than once within the family as the result of functional adaptation to efficient and safe water transport. Pseudo-tori are observed in species of Abeliophyllum, Fontanesia, Forsythia, Jasminum, Ligustrum, Menodora, and Syringa. Based on structural differences, we state that tori and pseudo-tori can be distinguished as non-homologous features.

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