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Results for “Microscopy, Phase-Contrast”

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At least 667 records · Page 37Linked to original sources
PubMed1976

[Refringence phenomenon as a sign of the degree of differentiation of immunocompetent cells].

Quantitative and qualitative analyses of the refringence phenomen in immunocompetent cells of various organs of rabbits and CBA line mice under conditions of immunological activity, as well as in those of children with ataxia-teleangiectasia, showed that immunoblasts contained predominantly non-refringent nuclei, mature plasmatic cells--mainly highly refringent nuclei, and young plasmatic cells occupied a position in the middle of the two. These data, as well as the absence of the refringence phenomenon in the cells of lymphosarcoma in man corroborate a direct relationship between the phenomenon and the process of differentiation of cells.

Animals↗
PubMed1976

Electron microscopic observations on the interaction of the myosin head subunit with actin in myofibrils.

Glycerol-extracted rabbit psoas muscle fibres were treated with a solution containing the head subunits of myosin. Interaction of the isolated myosin heads with actin filaments in situ was indicated by an increase in the density of the I-band and by an increased diameter of actin filaments alongside their whole length. We conclude that actin filaments are able to interact with a considerably larger number of myosin molecules than that available in the myofibril under in vivo conditions.

Actins↗
PubMed1976

[Ultrastructure of the proximal neurosecretory contact region in a sturgeon].

The proximal neurosecretory contact region (PCR), a homologue of the tetrapoda median eminence occupies the rostral and chiefly the ventral surfaces of the hypothalamic tuber cinereum. Three types of granule-containing neurosecretory fibres and their terminals have been found in the PCR with the electron microscope. Peptidergic, A1 and A2 type fibres contain granules of 120--300 nm and 100--170 nm in diameter, correspondingly, and monoaminergic B fibres have granules of 80--100 nm in diameter. Neurosecretory terminals and tanycyte vascular "endfeet" make contacts with a 70 nm thick outer basement membrane of the primary portal capillaries. Some thin horizontally oriented tanycyte branches form a multiserial layer bordering the external zone of the PCR from the preoptico-hypophyseal tract. Few neuroglial cells with pale cytoplasm and numerous lysosomes and lipofuscin granules are seen there. It is hypothesized that, like in other vertebrates, in the PCR of Acipenseridae both peptide and monoamine hypophysiotropic neurohormones may be discharged in the portal circulation to affect the functional activity of glandular cells of the pars distalis.

Animals↗
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↗