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Results for “MICROSCOPY, PHASE CONTRAST”

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At least 217 records · Page 12Linked to original sources
PubMed1972

Interference-contrast and phase-contrast microscopy of sporulation in clostridium thermosaccharolyticum grown under strict anaerobiosis.

Cells of Clostridium thermosaccharolyticum grown under strict anaerobiosis (modified Hungate technique) were examined during growth and sporulation by employing Nomarski interference-contrast and Zernike phase-contrast optics to delineate the sequence of morphological changes leading to the formation of free, mature spores. A 0.5% l-arabinose, liquid, complex medium was used to obtain a yield of 30 to 40% free, refractile spores (ca. 10(8)/ml) by 48 hr of incubation. The mean doubling time for the glucose culture (vegetative cells) was found to be 80 min, and that for the l-arabinose culture (sporulating cells), 498 min. By 8 hr of incubation, beginning spore formation became evident in the arabinose culture by the development of a distinct arrowhead-shaped terminal swelling. By 32 hr of incubation or shortly thereafter, Nomarski optics showed the mature spore to be uniformly spherical, whereas the enlarged terminal swelling containing it was not. The use of phase-contrast and interference-contrast optics permitted the characterization of the distinctive morphological changes occurring during sporulation of C. thermosaccharolyticum.

Agar↗
PubMed1987

Phase-contrast microscopy of the primate retina.

The study of hematoxylin and eosin stained thick sections (15 microns) of the primate retina with the phase-contrast microscope provided a means for the selective demonstration of many cellular structures that could not be resolved with the same degree of detail which was possible when bright-field microscopy was used, or when phase-contrast microscopy was employed to examine unstained material. The H & E-stain greatly enhanced the phase-contrast image, so that cytoplasmic structure, fiber trajectories, and gross synaptic detail of the retina could be demonstrated to better advantage.

Animals↗
PubMed1998

Cytohormonal evaluation of vaginal smears by phase contrast microscopy with special reference to progesterone deficiency pattern during early pregnancy as predictor of abortion.

Cytohormonal profile of unstained vaginal smears were studied under phase contrast microscope to define various cell morphologies in detail and build up of smear pattern serially in various stages of menstrual cycle and first trimester of pregnancy. The findings were correlated clinically and found comparable to Papanicolaou stained smears. The maturation index was calculated more objectively by phase contract microscopy because of the refractile appearance of the pyknotic nuclei of superficial cells. The prognostication of abortion was done by combining abnormal maturation index and the presence of syncytiotrophoblasts in vaginal smears. Under phase contrast microscope, the sensitivity of abnormal smear was 87.5%, the specificity was 95%, the positive predictive value was 96.55% and the overall accuracy was 90% as compared to positive Papanicolaou smear whose sensitivity though 93%, had low specificity of 50% only. Phase contrast study appears to offer certain distinct advantage over the conventional light microscopy for quick, comprehensive and quantitative assessment of the study material. It allows the physician to detect changes in the material obtained from the patients without detour of laboratory fixation and staining. It is technically easy as errors in interpretation due to unsatisfactory fixation, staining and artefacts are obviated. Thus phase contrast microscopy offers an alternative and easy method of cytohormonal evaluation of wet and unstained smears.

Abortion, Threatened↗
PubMed1998

A comparison of historic asbestos measurements using a thermal precipitator with the membrane filter-phase contrast microscopy method.

The published results and analytical methods used in a 1938 survey of the spinning area in a UK crocidolite asbestos factory have been described and re-interpreted, by comparing the method used with the current membrane filter-phase contrast microscopy (MF-PCM) method for asbestos. By good fortune, most of the original microscope, and thermal precipitator sampling heads similar to those used for sampling were available, as well as guidance from the factory inspector who collected and analysed the original samples. A textile grade crocidolite asbestos was used to generate a fibrous dust cloud whose size distribution was characterised by scanning and transmission electron microscopy and found to give a close approximation to the fibre size distributions monitored in 1938. Samples taken over the same sampling time, but at lower concentrations than originally sampled, showed that the thermal precipitator-oil immersion microscopy (TP-OI) method used at x 2000 magnification, gave higher > 5 microns long fibre counts by a factor of between 3 and 4, than the current MF-PCM method. The differences in performance could be explained by the superior resolving power of the TP-OI method for fine crocidolite fibres. Exposures of airborne asbestos fibres in the spinning area were found to be equivalent to about 20 f ml-1 for personal samples and 10 f ml-1 for area samples, but due to the high levels of ventilation on the day the samples were collected, the average levels throughout the year may have been somewhat higher.

Air Pollutants, Occupational↗