PLB 105 Lab Manual—Fall 2009
Microscopes and Microtechnique, Introduction to Plant Development
There are three primary goals in the first laboratory session. (1) Learn the correct use of the
compound microscope, (2) become adept at preparing plant tissues for microscopic study, and
(3) practicing these techniques while examining tissue and cell changes in developing seedlings.
The compound microscope is a primary tool in many diverse areas of research, including
the following: medical, plant, animal, microbe, metallurgy, and the computer industry.
Over the years, many college students have been introduced to the use of the compound
microscope, but few students learn how to take full advantage of this marvelous tool.
Your TA will demonstrate the correct use of the compound microscope. After you have
practiced using the microscope and have mastered its operation, your TA or proctor will
quiz you individually on its proper use. Each student must pass this short oral quiz before
the end of the second laboratory period.
Tissue manipulation and microtechnique must be mastered before you can effectively
study internal plant structure. In this lab you will be introduced to a few different
techniques and get a chance to practice using them. There will be ample opportunity to
use these and additional techniques as the quarter proceeds and your skills improve.
For fun, try to identify tissue types and some of the cell types seen today, but do not
spend much time on this.
You will learn ALL of these during the quarter.
B. Using the Compound Microscope
The TA will point out the following parts of the binocular light microscope:
c. Volt-meter knob
Eyepieces, or oculars, (10X). Both eyepieces can be focused.
Revolving nosepiece, or turret, with objective lenses. There are four objective lenses:
2.5X, 10X, 40X and 100X (i.e., oil immersion)—these may vary with different
microscopes. The 2.5X objective may be replaced by a different low-power objective
on some of the microscopes. When the microscope is not in use, the 2.5X objective
should be in position. Note: The 100X objective can retracted by pushing upward and
rotating counter clockwise. This lens should always be retracted when not in use.
Slide holder, mechanical stage, and stage movement controls
Below the stage is an accessory lens that is used with 10X and higher objective
lenses. When using the low-power objective, flip this lens out of the light path.
Condenser, including adjustable condenser diaphragm, focusing knob, and field
diaphragm centering knobs
Field diaphragm adjusting ring
j. Coarse-adjustment knob
k. Fine-adjustment knob
Operation and adjustment of the microscope
Check that the volt-meter knob is turned to 0, then plug in the cord. Place a slide in
the slide holder. Adjust the slide holder until the specimen on the slide is centered
within the field of view. Rotate the objective turret so that the 10X objective is in