1. OBJECTIVE
This experiment aims to enable you to handle a light microscope, an essential skill to support other activities within a laboratory.


At the end of this experiment, you should be able to:

Identify the basic components of the light microscope;

Understand the proper handling of the light microscope;

Understand basic focusing procedures.

2. WHERE TO USE THESE CONCEPTS?
The light microscope is a piece of equipment widely used in laboratories, both for research and clinical analysis. This is because it allows us to distinguish tiny structures that could not be observed with the naked eye. Therefore, many analyses, observations and findings are possible using this important tool.

Correct use of the microscope allows the user to have an excellent view of the structure to be analyzed. For example, imagine that you need to analyze a blood sample from a patient, looking for a parasite, such as Plasmodium (the etiological agent of malaria). The correct adjustment of the microscope structures allows the image formed to be clear enough to distinguish the parasite from a platelet (blood cell component), for example.

Therefore, you need to understand what the microscope's components are and their functions, in order to make the best possible use of this tool.


3. THE EXPERIMENT
In this experiment, the light microscope will be used. The first phase is the identification of each part of the device and the differentiation of its mechanical and optical functions. In the second phase, you will prepare a simple staining slide, with buccal scraping material stained with methylene blue. To do this, you must collect the material from the oral mucosa with the help of a sterile swab, and smear it on the slide.

After this step, you must fix the material with 70% alcohol. The staining, as already mentioned, will be done with methylene blue. After removing the excess dye with distilled water, the prepared slide will be viewed under a microscope with a drop of distilled water under the smear, and then covered with a coverslip, taking care to avoid the formation of bubbles. The visualization will be done under a microscope, properly carrying out all the procedures to safely turn on the device and adjusting the mechanical and optical parts that you previously analyzed. Visualization should begin with the lowest magnification objective, progressing to the highest. Don't forget the immersion oil when it's time to view with the 100x objective. After viewing it through all the objectives, you must clean the device and take steps to turn it off. All material used must be disposed of properly, in accordance with biosafety standards.


4. SECURITY
To carry out this practice, in accordance with biosafety rules, you must wear long pants (preferably jeans; avoid leggings), closed shoes (completely covering the back of the foot) and, in case of long hair, you must keep your them secured with an elastic band throughout their stay in the laboratory. Although the material used offers a low biological risk, especially if it is your own sample, it is important to understand that, even so, it is a biological sample and, as such, must always be considered contaminating. Furthermore, the use of dyes can pose a risk, as they are a chemical agent; therefore, the use of protective gloves while carrying out the practice is essential. It is also important to highlight that appropriate clothing and the use of a lab coat offer protection against possible spills and splashes, delaying contact with the skin. Closed-toe shoes, in addition to preventing substances from coming into contact with the skin, also prevent the possibility that, if a blade and/or cover slip falls on your foot, it causes cuts and punctures.