2. Types of Microscopes:
1. Compound Light Microscope (what we
use most often)
2. Stereoscopes – also known as dissecting
scopes
3. Electron Microscopes
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3. Parts of the Microscope
Arm
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4. Parts of the Microscope
Diaphragm
Light Source
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5. Parts of the Microscope
Stage
Stage Clips
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6. Parts of the Microscope
Revolving
Nosepiece
Objective
Lenses
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7. Parts of the Microscope
Ocular Lens
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8. Parts of the Microscope
Coarse adjustment knob
Used only when low power objective is used!!
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9. Parts of the Microscope
Fine adjustment knob
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10. Important Vocabulary :
magnification mag-ne-fe-'ka-shen n 1.
apparent enlargement of an object 2.
the ratio of image size to actual size
A magnification of "100x" means
that the image is 100 times bigger
than the actual object.
resolution rez-e-loo-shen n 1. clarity,
sharpness 2. the ability of a
microscope to show two very close
points separately
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12. Parts of the Microscope
Arm
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13. Steps to Use:
1. Rotate the low power objective into place and make sure the
stage is all the way down.
2. Place slide on stage making sure object to be viewed is
centered over the hole in the stage. Use the stage clips to
hold the slide in place.
3. Turn light on.
4. Focus first with the coarse adjustment knob. Once in focus on
low power, turn the nosepiece until the next higher lens is in
place.
5. Use FINE adjustment knob ONLY and focus the object.
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14. Techniques of Light Microscopy
• Preparation of Specimens for the Light
Microscope:
• 1) Wet Mounts- drop of medium with
microbes is spread on a slide
• 2) Smears- microbes from a loopful of
medium are spread on a slide, then heat
fixed to kill microbes
- heat fixationDr. Ashish V. Jawarkar
17. Principles of Staining
• Stain- dye that binds to a cellular structure
and gives it color
• + charge-basic= methylene blue, crystal
violet, safranin and malachite green
• - charge-acidic= eosin and picric acid
• Simple stain- single dye and reveals basic
cell shapes and structures
• Differential stain- 2 or more dyes: Gram
stain, Ziehl-Neelsen acid fast and spore
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18. Gram Stain
• Gram Stain- 1884 crystal violet (+) and
iodine and ethanol decolorizer, and
counterstained with safranin (-)
• Gram +=purple
• Gram - = red
• Gram non reactive= no stain
• Gram Variable= stain unevenly
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19. Special Staining Procedures
• Ziehl-Neelsen Acid-Fast Stain
- 1882 modification of Ehrlich staining
method
- Acid fast retain red color in cell walls
• Negative staining-capsule is present and
won’t take up stain
• Flagellar staining- coats flagella so they
can be seen
• Endospore staining- Schaeffer-Fulton stain
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20. Recording what you see:
Include:
1.
Figure #: and Title
2.
Labeled drawing of the field of view. Label on the right using straight lines which
should never cross.
3.
Common and scientific name of organism.
4.
Magnification you were viewing when you drew the organism: ocular X objective
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21. Remember:
1. If you are seeing perfectly round, clear circles then you
just may be looking at air bubbles. Check your slide and
try again.
2. Microscopes must always be properly put away.
3. Slides and cover-slips should be washed, dried, and
returned to their proper place.
Dr. Ashish V. Jawarkar