Bright-field microscopy

There are three primary image modes that are used in conventional TEM work, bright-field microscopy, dark-field microscopy, and high-resolution electron microscopy. In practice, the three image modes differ in the way in which an objective diaphragm is used as a filter in the back focal plane. 

In bright-field microscopy, a small objective aperture is used to block all diffracted beams and to pass only the transmitted (undiffracted) electron beam. In the... 

A) Bright-field microscopy. The silver-enhanced gold appears as a dark stain. 

Fig. 4.3 Bright field microscopy of palisade peels from soybeans at early maturation stage (400-500 mg fresh seed weight), (a) Black (Clark) with AVIs (black arrowheads), (b) Red-brown (Ml 1). Scale bar = 20 (jim. Effect of oxidation on seed coat color demonstrated by exposing immature seeds (400-500 mg fresh seed weight) (c-f) to air for 2 h (g-j). (c, g) Black (Clark), (d, h) red-brown (Mil), (e, i)brown (MlOO), and (f, j) yellow (Qark)...

In the conventional bright field microscopy, light from an incandescent source is sequentially transmitted through the condenser, the specimen, an objective lens, and a second magnifying lens, the ocular or eyepiece, prior to reaching the eye. Some microscopes have an internal illuminator, while... 

Bright field microscopy is suitable to observe stained bacteria, thick tissue sections, thin sections with condensed chromosomes, large protists or metazoans, living protists or metazoans, algae, and other microscopic plant material. 

Fig. 1. Small intestine formaldehyde-fixed, paraffin-embedded. Section was stained with Concanavilin A conjugated to 5-nm colloidal gold. The gold was then silver-enhanced. Staining of mucous on the cell surface and in goblet cells is seen. (A) Bright-field microscopy. The silver-enhanced gold appears as a dark stain. (B) Epipolarization microscopy. The silver-enhanced gold appears bright against a dark background.

A EXPERIMENTAL FIGURE 5-44 Live cells can be visualized by microscopy techniques that generate contrast by interference. These micrographs show live, cultured macrophage cells viewed by bright-field microscopy (/eft), phase-contrast microscopy middle), and differential interference contrast (DIC) microscopy righti. In a phase-contrast image, cells... 

Labels are molecules that can be attached to antibodies and will localize the antibodies in cells and tissues. For bright field microscopy, enzymes are the best compounds to label antibodies. Enzymes allow amplification wifh development of reaction products for labeling. A second approach for bright field microscopy is the use of particulates, such as enhanced gold or silver. The third approach is the popular fluorescent labels. In this chapter, the different types of labels are examined. In subsequent chapters, the methods of applying labeled antibodies will be examined. 

Figure Bl.18.4. The most frequently used illumination system in bright-field microscopy.

Fig 2 and 3 show granules of PHA inside Poly-P bacteria stained with Nile blue by bright field microscopy and by epyfluorescence microscopy,... 

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