how to prepare microscope slide?

One of the most commonly used teaching aid in biology is how to prepare microscope slide. If you’re involved in biological research, chances are at some stage you’ve submitted specimens to a lab. Somehow they magically produced beautiful slides for you – each containing thin sections of your specimens, ready for microscopic evaluation.

Most biology student and teacher, especially those in high schools and introductory courses in colleges, will use prepared microscope slide some time or other.

The techniques that are used in preparing microscope slides are so numerous that allow us advanced viewing of inorganic and organic objects. However, most of them can not even be mentioned here; but some of them that can be applied universally, that we are discussed here.

What is the Type Of Microscope Slide?

There are two types of microscope slides that are generally used for the mounting technique.

  1. Flat Slide
  2. concave slide.
how to prepare microscope slide?

1) Flat Microscope Slide.

The basis of all microscope slides is a flat rectangular soda lime glass. borosilicate cover glass or transparent plastic.

All corners of the slide are a sharp 90 degrees and along with a rough outer edge, it can cause minor finger cuts if not handled with care.

The top and/or bottom edges of a slide can be frosted, enabling easy marking for sample identification and/or orientation. The etched frosting keeps all pen marks safely away from the sample and a selection of frosted colors provides additional means of categorization.

Rounded safety corners to prevent accidental cuts as well as beveled edges with clipped corners ideal for blood samples are options available for both generic and frosted slides.

2) Concave microscope slide.

Concave microscope slides contain one or more surface depressions ideal for liquid solutions and larger specimens. These more expensive microscope slides can be used without a cover.

Some manufacturers produce plastic chambers with a predetermined number of slides with covers.

Filled calibrated wells or flasks are viewed quickly without preparing or clipping individual slides to the microscope stage, making this especially useful in sediment studies, such as urine analysis; in addition, some tray designs can be placed in an incubator or refrigerator, allowing for the study of cultured samples.

Microscope Slide Preparation Techniques: Dry Mounts, Wet Mount, Squash, Staining

The main methods of placing samples onto microscope slides are wet mount, dry mount, smear, squash, and staining.

1) Wet Mount Slides:

Used for aquatic samples, living organisms, and natural observations, wet mounts suspend specimens in fluids such as water, brine, glycerin, and immersion oil. A wet mount requires a liquid, tweezers, a pipette, and paper towels.

To prepare the slide:

  • Place a drop of fluid in the center of the slide
  • Position the sample on liquid, using tweezers
  • At an angle, place one side of the coverslip against the slide making contact with the outer edge of the liquid drop
  • Lower the cover slowly, avoiding air bubbles
  • Remove excess water with the paper towel

If the sample won’t stay on the slide, it may be secured by painting the slide with clear nail polish immediately before adding the specimen. This also makes the slide semipermanent. Usually, slides can be rinsed and reused, but using nail polish means the slides must be cleaned with polish remover before reuse.

2) Dry Mount Slides:

Dry mount slides can consist of a sample placed on a slide or else a sample covered with a coverslip. For a low-power microscope, such as a dissection scope, the size of the object isn’t critical, since its surface will be examined. For a compound microscope, the sample needs to be very thin and as flat as possible. Aim for one cell thickness to a few cells. It may be necessary to use a knife or razor blade to shave a section of the sample.

  • Place the slide on a flat surface.
  • Use tweezers or forceps to place the sample on the slide.
  • Place the coverslip on top of the sample. In some cases, it’s okay to view the sample without a coverslip, as long as care is taken not to bump the sample into the microscope lens. If the sample is soft, a “squash slide” may be made by gently pressing down on the coverslip.

If the sample won’t stay on the slide, it may be secured by painting the slide with clear nail polish immediately before adding the specimen. This also makes the slide semipermanent. Usually, slides can be rinsed and reused, but using nail polish means the slides must be cleaned with polish remover before reuse.

3) How to Make a Blood Smear Slide:

Some liquids are either too deeply colored or too thick to view using the wet mount technique. Blood and semen are prepared as smears. Evenly smearing the sample across the slide makes it possible to distinguish individual cells. While making a smear isn’t complicated, getting an even layer takes practice.

  • Place a small drop of a liquid sample onto the slide.
  • Take a second clean slide. Hold it at an angle to the first slide. Use the edge of this slide to touch the drop. Capillary action will draw the liquid into a line where the flat edge of the second slide touches the first slide. Evenly draw the second slide across the surface of the first slide, creating a smear. It’s not necessary to apply pressure.
  • At this point, either allow the slide to dry so that it can be stained or else place a coverslip on top of the smear.
How to Make a Blood Smear Slide

4) Squash Slides:

Designed for soft samples, squash slides begin by preparing a wet mount; place lens tissue over the cover glass; gently press down, careful not to destroy the sample or break the cover glass, and squash the sample; remove excess water.

5) Staining slide:

A variety of methods exist for staining microscope slides, including non-vital or in vitro stains of non-living cells and vital or in vivo stains of living tissue. Staining provides contrast through color that reveals structural details undetected in other slide preparations.

Staining solutions such as iodine, methylene blue, and crystal violet can be added to wet or dry mounts.

A simple staining method:

  • Add a drop of staining solution on the edge of one side of the coverslip
  • Position the edge of a paper towel on the opposite end
  • Allow the dye to be pulled across the specimen

Stains are especially useful in the fields of histology, virology, and pathology, allowing researchers to study and diagnose diseases, identify gram-positive and negative bacteria as well as examine detailed attributes of a variety of cells.

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