Microscopy Basics and Techniques

Using a Microscope

• Start with the lowest magnification (4X, red)
• Place the slide on the stage and lock the clips
• Do not use the coarse adjustment knob at high magnification. It may break the slide.
• Use the coarse adjustment knob from up to down
• Adjust the light source. If using a mirror, do not stand in front of it
• Use the fine adjustment knob to focus

Specimen or Slide

• The specimen is the object being examined
• Most specimens are mounted on slides, flat pieces of thin glass
• A coverslip is placed over the specimen on the glass
• This allows the slide to be easily inserted, removed, labeled, transported, and stored

What is a Wet Mount?

• A wet mount is a preparation where the specimen is suspended in a drop of liquid, typically water, placed between the slide and coverslip
• The water improves the image quality and supports the specimen

Making a Wet Mount

• Place a small drop of water in the center of the microscope slide
• Place the specimen into the water
• Add more water to ensure the specimen is completely submerged
• Hold the cover glass at an angle with tweezers and slowly lower it onto the water drop to minimize air bubbles
• Remove excess water with filter paper or tissue paper

Laboratory Applications

• Create a wet mount of starch using water
• Make another wet mount using I₂ solution
• Boil plant powder with 5% KOH for 5 minutes and create a wet mount
• Make a mount of the boiled plant powder with phloroglucinol + conc.HCl

Lab 2: Starches

• Starches (Amylum) are the principle form of carbohydrates in green plants
• Common starches are present in grains (wheat, maize) and underground organs (potato, ginger)

Caring for a Microscope

• Clean only with a soft cloth/tissue
• Clean eyepiece and object lenses using water or xylene
• Ensure it is on a flat surface
• Avoid banging it
• Do not leave the light on when not in use

How to Carry a Microscope Correctly

• Use two hands: one on the arm and one on the base

Microscope Parts and Functions

• Arm: connects the body tube to the base of the microscope
• Stage clips: hold microscope slides in place. If the microscope has a mechanical stage, there are knobs to move the slide around (left/right and forward/backward).
• Stage: The flat platform where microscope slides are placed.
• Illuminator: A steady light source, replacing a mirror in some models.
• Diaphragm/Iris: A rotating disk under the stage with different-sized holes to vary the intensity and size of the light cone projected onto the slide.
• Coarse adjustment: Brings the specimen into general focus.
• Fine adjustment: Fine-tunes the focus and increases the detail of the specimen.
• Important Note: When focusing, carefully avoid the objective lens touching the slide to prevent breakage.