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Results for “Microscopy, Phase-Contrast”

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At least 613 records · Page 34Linked to original sources
PubMed1975

[Realization of systemic relations in the behavior of early neuroblasts in nerve tissue cultures].

When cultivating the nervous tissue of newborn rats, rabbit embryos and tadpoles (as whole fragments or dissociated cells), 3 groups of neuroblasts are distinguished: differentiating, migrating and with growing processes. These groups correspond to different stages of neuroblast development in vivo and their presence in the tissue cultures of different brain regions reflects the heterochrony of cell development in these regions. The neuroblasts realize their morphogenetic potential within several days of cultivation irrespective of the contact with the other cells but the subsequent differentiation (dendrite branching, nuclear clearance etc.) proceeds only in cells united in aggregates.

Animals↗
PubMed1975

[Fluorescence bacterioscopy, a direct method for bacteriological food analysis].

The present bacteriological method which is intended for the simultaneous direct detection of live and dead germs in foods, offers certain difficulties in differentiating between bacterial cells and food consituents of similar forms. Furthermore, gram-negative germs are not disclosed. To overcome these difficulties, the authors performed comparative model experiments with Gram's stain and the fluorescence method, including pure cultures and foods of animal and vegetable origin. Among the fluorochromes tested (primuline, auramine, acridine orange and acridine yellow), acridine yellow has proved to be specially suited and superior to Gram's stain. A method is described which is termed fluorescence bacterioscopy. Its advantages and disadvantages are discussed.

Acridines↗
PubMed1978

[Morphological virus diagnosis--electron microscopy study of animal viruses with negative contrast procedure].

Reported in this paper are results obtained in morphological virus diagnosis by using the negative contrast technique on the basis of electron microscopy. The availability of high-efficiency electron microscopy as well as of perfectly improved techniques of preparation, knowledge of the latest virus model concepts, and indivudual skills in diagnosis are essential conditions for the above approach. Parvoviridae, picornaviridae, and togaviridae are identifiable only in high particle concentrations and by group representation. Papovaviridae, adenoviridae, herpetoviridae, poxviridae, and reoviridae, on the other hand, can be safely identified even as single particles. The diagnosis of orthomyxoviridae, paramyxoviridae, rhabdoviridae, and retroviridae is facilitated by their own dimensions and their characteristic helico-symmmetrical nucleocapside. Coronaviridae are of highly conspicuous morphology but, nevertheless, pose problems in differential diagnosis. Substantive improvement of morphological virus diagnosis, in terms of minute details, may be achieved by means of the negative contrast method on the basis of immune electron microscopy. Advantages implied in that morphological method include less time-consuming and quite uninvolved practicability and good dependability of diagnosis for more efficient decision-making in research and practice.

Animals↗
PubMed1978

The preparation and ultrastructure of avian erythrocyte nuclear envelope enclosed by the plasma membrane.

A procedure is described for the preparation of avian erythrocyte nuclear envelope ghosts which remain enclosed by the ellipsoid plasma membrane. Haemoglobin-free nucleated chicken erythrocyte ghosts are treated in a low ionic strength buffer plus heparin which brings about decondensation of the chromatin. This is followed by solubilization of the chromatin by digestion with pancreatic deoxyribonuclease-1. When studied by light microscopy using either phase-contrast or Nomarski interference optics, the ellipsoid plasma membrane is clearly seen to remain with the collapsed nuclear envelope trapped inside. This interpretation is supported by negative-staining electron microscopy using ammonium molybdate, which in addition reveals the presence of the nuclear pore complexes. The suggestion is advanced that structural protection is provided for the fragile nuclear envelope system by the surrounding plasma membrane, which might account for the final nuclear envelope being in the form of relatively intact ghosts with well defined nuclear pore complexes. The nuclear envelope is highly fragmented when the plasma membrane is absent, the nuclear pore complexes showing appreciable breakdown. Thin sectioning supports the results of negative staining and in addition shows the nuclear envelope retained within the plasma membrane to be composed of both inner and outer nuclear membranes, but the nuclear pore complexes are not clearly defined.

Animals↗
PubMed1976

Morphological and physiological characteristics of Gemmiger formicilis isolated from chicken ceca.

Morphological and physiological studies were made on chicken cecal isolates of the strictly anaerobic bacterial species Gemmiger formicilis. Structural features (phase-contrast and electron microscopy) of these microorganisms indicate they (i) are highly pleomorphic, (ii) possess a trilaminar cell wall like gram-negative bacteria, (iii) exhibit an unusual growth process characterized by polar swelling (resembling budding bacteria), and (iv) grow into elongated cells when exposed to a subinhibitory concentration of penicillin. The morphological data presented suggest that this species has a rod-shaped structure. These bacteria ferment a variety of sugars to produce formic, butyric, and lactic acids. There appear to be two groups of Gemmiger, one producing primarily lactate and the other producing formate as major fermentation metabolites. Growth of six strains in a basal medium, consisting of Trypticase, minerals, carbohydrate, Na2CO3 buffer, and cysteine as reducing agent, was stimulated by rumen fluid and yeast extract. Volatile fatty acids partially replaced the requirement for rumen fluid with some strains. Single deletions of vitamins (from a defined vitamin mixture) indicated that pantothenate, riboflavin, and thiamine were highly stimulatory to growth of the organism in a medium containing rumen fluid and Trypticase as source of vitamins. Other vitamin requirements were not studied.

Acetates↗
PubMed1978

An insect cell line persistently infected with a baculovirus-like particle.

A persistent infection by a baculovirus-like particle was found in the established lepidopteran (Heliothis zea) cell line, IMC-HZ-1. The virus caused CPE in less than 1% of the IMC-HZ-1 cells, as measured by phase-contrast and electron microscopy. Transmission tests showed that four lepidopteran cell lines were susceptible to the persistent virus (designated as IMC-HZ-I-NOV). In inoculated TN-368 cell cultures, 90--100% infection was achieved. The ultrastructure and development of IMC-HZ-I-NOV in cell cultures were similar to known baculoviruses, and it is probable that this persistent virus is a member of the family Baculoviridae. Two lepidopterous species (Estigmene acrea and H. zea) inoculated with IMC-HZ-1-NOV by intrahemocoelic injection and/or per os feeding of larvae were not susceptible.

Cell Line↗
PubMed1977

Tissue culture isolation and preservation of human cadaveric pancreatic islets.

Six specimens of human cadaveric pancreas were collagenase-dispersed and placed in tissue culture. Media were changed at 2 day intervals and assayed for insulin and amylase. Experiments were terminated after 8 days, and phase-contrast and light microscopy were performed on cultured tissue. Insulin content in media remained high for 6 days in five cases and for 8 days in four experiments; this correlated directly with morphologic viability of cultured tissue. Media amylase fell to zero after 4 days in four cases and after 6 days in two cases. These data support the concept that tissue culture may be an efficient method for (1) islet cell purification, since acinar tissue and amylase activity disappear, and (2) islet preservation.

Adult↗
PubMed1978

Attachment of virulent Treponema pallidum to human mononuclear phagocytes.

The predominant phagocyte in established human syphilitic lesions is the mononuclear phagocyte. As these leucocytes may be important in immunity to Treponema pallidum, the initial interaction between human phagocytes and pathogenic T. pallidum (Nichols strain) was studied in vitro. Motile, virulent T. pallidum attach to the surface membrane of phagocytes but are not ingested by these cells. Heated, non-motile treponemes are not cell-associated but are observed free in the extracellular medium. Attachment is polar, at one or both terminal portions of the treponeme, and is neither serum- nor complement-dependent. Ingestion of virulent treponemes was not observed by phase-contrast or by electron microscopy in the presence of normal human or rabbit serum and complement. Techniques were chosen to preserve both the fragile surface constituents of the treponeme and the phagocytic function of mononuclear cells. Unfixed preparations were observed by phase-contrast microscopical examination during incubation to differentiate motile from non-motile organisms and fixed preparations were used for quantitation of attachment. This model should be useful for studying humoral and cell-mediated immunity in syphilis.

Cell Adhesion↗
PubMed1978

Light and electron microscopic histochemistry of the monoamines in the human foetal sympathetic ganglion in culture.

Sympathetic ganglia of 13 to 19-week-old human foetuses were cultured in small pieces with and without nerve growth factor for up to 5 weeks in vitro. The cultures were studied using phase-contrast, fluorescence and electron microscopy. Monoamines were demonstrated with the formaldehyde-induced fluorescence method, with and without pretreatment of the cultures with catecholamines or monoamine oxidase inhibitor. In the long-term cultures, primitive sympathetic cells, sympathicoblasts of types I and II, and young sympathetic neurons showed a fine structure identical to that described earlier in vivo. There were virtually no satellite or Schwann cells in the cultures. The neurons showed a considerable capacity to grow new nerve fibres in culture, even without nerve growth factor. Nerve terminals with accumulations of synaptic vesicles were regularly observed, occasionally in synapse-like contact with other nervous structures. Large granular vesicles were regularly found in the sympathicoblasts after glutaraldehyde-osmium tetroxide fixation. After permanganate fixation, dense-cored vesicles typical of adrenergic neurons were not seen, either in the perikarya, or in the processes, although it was possible to demonstrate specific fluorescence. No small intensity fluorescent (SIF) cells were observed. Variable formaldehyde-induced fluorescence was observed in the nerve cell perikarya and nerve fibres. The intensity of the fluorescence increased after treatment of the cultures with monoamine oxidase inhibitor and after incubation with catecholamines.

Axons↗