3. Temporary Slides
+ made for the purpose of short time
observations.
+ After the observation session, they are
discarded.
+ In most cases the slides use a liquid
mounting medium, such as water.
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6. 1. Sectioning
- is an important step for the preparation of
slides as it ensures a proper observation of
the sample by microscopy.
- Sections are cut on a precision instrument
called a “microtome” using extremely fine
steel blades.
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7. 2. Staining
- increases contrasts in order to recognize and
differentiate the different components of the
biological material.
- Apart from a few natural pigments such as
melanin, the cells and other elements making
up most specimens are colorless. In order to
reveal structural detail using brightfield
microscopy, some form of staining is required.
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8. STAINS
+ Stains are used to help identify different
types of cells using light microscopes. They
give the image more contrast and allow cells
to be classified according to their shape
(morphology)
+ Stains can also help differentiate between
living or dead cells.
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9. + Stains tend to be grouped as neutral, acidic or
basic, depending upon their chemical makeup
and will attract or repel different organisms
accordingly.
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11. Iodine
+ is one of the more commonly available stains
and is used to identify starch in a variety of
samples.
+ It will stain carbohydrates in plants and animal
specimens brown or blue-black.
+ Glycogen will show as red.
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12. Methylene Blue
+ is an alkaline stain useful in identifying acidic
cell nuclei and DNA in animal, bacteria or blood
samples.
+ It’s also useful in aquariums to prevent the
spread of fungal infections in fish.
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13. Eosin Y
+ is an acidic stain which stains pink for alkaline
cells (cytoplasm, for example).
+ It colors red for blood cells, cytoplasm and cell
membranes.
+ Eosin's most important medical uses are in
blood and bone-marrow testing, including the
PAP smear.
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14. Gram's Stain
+ is one of the most frequently used processes in
identifying bacteria – used daily in hospitals.
+ It is a primary test that quickly and cost
effectively divides bacteria into one of two
types: Gram positive or Gram negative.
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15. 3. Mounting
- Sections are mounted between slides and
coverslips using a product to ensure adhesion.
The slides are then ready for storage or
observation.
- For fluorescence microscopy observations, a
mounting medium is used in order to
temporarily decrease the fluorescence loss.
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17. Dry Mount
+ In a dry mount, the specimen is placed directly
on the slide. A cover slip may be used to keep
the specimen in place and to help protect the
objective lens.
+ Dry mounts are suitable for specimens such as
samples of pollen, hair, feathers or plant
materials.
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18. Wet Mount
+ In a wet mount, a drop of water is used to
suspend the specimen between the slide and
cover slip.
+ Wet mounts are suitable for studying water-
bound organisms such as paramecium or
bodily fluids such as saliva, blood and urine.
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19. Section Mount
+ In a section mount, an extremely thin cross-
section of a specimen is used. Using a microtome,
cut a thin slice of your selected specimen such as
an onion, and carefully set it on your slide.
+ Section mounts are suitable for useful for a wide
variety of samples such as fruit, vegetables and
other solids that can be cut into small slices.
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20. Smear
+ A smear is made by carefully smearing a thin
layer of the specimen across a slide and then
applying a cover slip. Typically, a smear should
be allowed to air dry before applying a stain.
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21. Steps in preparing temporary slides
+ Place a drop of fluid in the center of the slide.
+ Position sample on liquid, using tweezers.
+ At an angle, place one side of the cover slip
against the slide making contact with outer
edge of the liquid drop.
+ Lower the cover slowly, avoiding air bubbles.
+ Remove excess water with the paper towel.
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