Biophotonics_Concepts_to_Applications

• Brightfield microscopyis commonly used to observe color and light intensity
  (brightness) information from a stained specimen. The entire specimen section
  being examined is illuminated and appears bright to the viewer. Most specimens
  are fairly transparent under the microscope and consequently are difficult to
  analyze visually against a plain white background. Thus,cell stainingcan be
  used to add color to the picture, thereby making objects such as cells and their
  components much easier to see. Through the use of different stains, certain cell
  components (e.g., a nucleus, a cell wall, or the entire cell) can be selectively or
  preferentially stained to examine the component structure. Staining may also be
  used to highlight metabolic processes or to differentiate between live and dead
  cells in a sample. However, it is important to note that because the specimen is
  stained prior to being viewed under a microscope, the observed colors are not
  necessarily those of the actual specimen.

Turret with

objective lenses

Stage plate

Light source

Eyepiece

Specimen holder

(e.g., petri dish)

Light path

Fig. 8.3 Example of an
inverted microscope

Rotating objectives

Stage plate

Stereo

eyepiece

Specimen (plant,

zebra fish, mouse)

Bottom illumination

Top illumination

Stereo head

Fig. 8.4 Example of a
stereomicroscope

238 8 Microscopy