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2. Place the slide on the microscope stage. At low magnification, find an area with a minimal
number of bubbles. Work your way up to a 400x image.
3. Manipulate the condenser diaphragm until you obtain an image that has the best contrast.
4. Sketch this image in your lab notebook.
5. Perfuse a drop of acetocarmine under the cover slip as described in the section below. The best
staining will occur near the edge of the tissue.
6. Repeat steps 2 - 4 above.
Potato slice. Here you will make a wet mount of a thin section (slice) of potato tissue. Your TA
will give you some tips about how to make a section that is thin enough without hurting yourself.
Once you can do this with ease, proceed as follows:
1. Make a wet mount of a small thin section of potato.
2. Proceed as described in steps 2 - 6 for the onion epidermis with the exception of substituting
I2KI for the acetocarmine used in step 5. The thinnest edge of the tissue will be the best place
for making your observations.
Cheek epidermal cells. Here you will observe the epidermal cells lining the inside of your cheeks.
Use the flat end of a toothpick to scrape the inside of your cheek to remove some of these cells. Gentle
pressure is all that is needed. Proceed as follows:
1. Make a wet mount of your cheek cells using a drop of your saliva as the mounting liquid.
2. Proceed as described in steps 2 - 6 for the above tissues with the exception of substituting 0.1%
toluidine blue for the stain. Be careful not to withdraw liquid from under the cover slip too
quickly - you might sweep the cells from under the cover slip.
This concludes the practical part of this laboratory session. Please go to item III in the
SUMMARY OF MICROSCOPE USE PROCEDURES on how to properly conclude a microscopy
When finished, you should write a short summary (a sentence or two should be sufficient) of your
results for each of the four contrast enhancing techniques (that is one for the condenser manipulation
and one each for the three stains). Then you should use your results to compare and contrast the
structure and composition of the cells that were examined.
*** Biology 05LA – Fall Quarter 2012 Lab 1 – page 9 SUMMARY OF MICROSCOPE USE PROCEDURES:
I. Obtaining the desired image with your microscope:
1. Starting checklist:
a. Plug in the ‘scope, turn on the sub-stage illuminator, and raise the brightness to an
b. Check to see that the low power (4x) objective is in position. If it is not, use the edge of
the revolving nosepiece to move it into position.
c. Check to see that the condenser assembly is close to its uppermost possible position. If
not, use the condenser focus control to move the condenser assembly upward.
d. Check to see that the condenser diaphragm is not completely closed.
2. With a slide on the stage of the microscope, open the movable slide clamp by pushing it to the
left and position the slide so that it can be held by the clamp. Remember that the slide clamp
holds the slide by its edge.
3. Using the stage motion controls, move the slide so the object you wish to observe is positioned
directly over the condenser. (If you cannot see the specimen, you can focus on the edge of the
cover slip – this will give you an adequate starting focus.)
4. While looking at the microscope stage from the side, carefully move the stage to its uppermost
position with the coarse focus control.
5. While looking through the microscope, slowly lower the stage with the coarse focus control
until an image of your specimen appears. Sharpen the focus with the fine focus control.
6. If higher magnification is required, center an important feature of your specimen in the field of
view and sharpen the focus using the fine focus control. Then rotate the revolving nose piece
so that the next strongest objective clicks into position. Some slight focusing will be necessary
here to produce a sharp image of the specimen.
7. If still higher magnification is required, repeat step 6.
II. Changing slides:
1. Rotate the low power (4x) objective into position. Because of the long working distance of this
objective, THERE IS NO NEED TO LOWER THE STAGE WHEN CHANGING SLIDES.
2. Remove the slide from the grasp of the slide clamp.
3. Insert the new slide into the slide clamp and move the specimen into the light path. If the focus
was not changed, the new specimen should be in close enough focus for beginning your work.
III. Concluding the microscopy session:
1. Rotate the low power (4x) objective into position and remove the slide from the grasp of the
slide clamp. DO NOT LOWER THE STAGE!!
2. Using the stage motion controls, center the stage mechanism over the stage.
3. Clean the ocular lenses and the 40x objective if necessary.
4. Turn off the illuminator. Biology 05LA – Fall Quarter 2012 Lab 1 – page 10 Two Useful Microscope Techniques
Making of wet mounts:
A wet mount is a common form of specimen preparation for light microscopy that is used for the
observation of a wide range of spec...
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- Fall '12