Slides for university students are usually prepared in the histology lab. Students in medical sciences are often trained to know what a tissue is when placed on a slide. The essence is for them to be able to identify anomalies or deviations from the standard ones. However, before they can start taking any of the required lectures, the lab technologists must take the tissues through some histology techniques to prepare microscope slides.
There are different kinds of microscopes the students can use in the lab. The ones to be used should depend on what they will be asked to identify as well as the conditions in the laboratory. They include the electron, light, phase contrast, fluoresce, confocal microscopes.
The parts of a light microscope include the presence of lamp, iris, diaphragm, tube and lenses, eyepiece, adjustment knobs, and objective lens. There are usually three types of adjustment knobs, and they include condenser height, fine and coarse knobs. Their major function is to control the clarity of what is being viewed.
After the microscopes have been made available, the next step would be tissue processing. This involves different steps such as fixation, dehydration, clearing, wax impregnation, embedding, sectioning, clearing, staining, and mounting. Each of these steps has its own chemicals and their compositions must be applied strictly to avoid any distortion from what the slides should be after preparation.
When a cell dies, the first thing that must be done is the fixation. Fixation is the process taken to prevent putrefaction. The method involves soaking the tissue in chemicals known as fixatives and they include salt, Bouin's fluid, and buffered formalin. Apart from the use of chemicals, the tissue can be heated or kept inside a refrigerator. The ratio of the volumes of fixatives to the tissue should be 3:1. It is important to use more fixatives so that the tissue can be well covered.
Fixation usually introduces water that must be removed through the process called dehydration. Since alcohol and water are miscible, alcohol can be used in the process. The concentration of alcohol used should vary from low to high and in an ascending order. It is good to do it with 50%, 50%, 75%, 75%, 98%, and 98% alcohol concentrations one after the other. This is necessary to remove all bubbles and to prevent the possibility of shrinking.
The alcohol introduced into the tissue must not be left for long. The process involved in getting rid of it is known as clearing. It is done with clearing agents such as xylene, benzene, chloroform, and toluene. After this, wax is impregnated into the tissues so as to remove xylene. In addition to xylene removal, waxing makes it easy to cut the tissues and the cuts are also strong.
Dewaxing must be done in the end. In dewaxing, the tissue has to be rehydrated so as to bring it back to water. Rehydrating is done with alcohol, but this time in descending grades. You can start with 98% alcohol and stop with 50% alcohol. Of course, water will also be used in this process. The tissues are then stained with some special dyes such as Periodic Acid Schiff, Van Gieson, Masson trichrome, Sudan black, and Osmium tetroxide.
There are different kinds of microscopes the students can use in the lab. The ones to be used should depend on what they will be asked to identify as well as the conditions in the laboratory. They include the electron, light, phase contrast, fluoresce, confocal microscopes.
The parts of a light microscope include the presence of lamp, iris, diaphragm, tube and lenses, eyepiece, adjustment knobs, and objective lens. There are usually three types of adjustment knobs, and they include condenser height, fine and coarse knobs. Their major function is to control the clarity of what is being viewed.
After the microscopes have been made available, the next step would be tissue processing. This involves different steps such as fixation, dehydration, clearing, wax impregnation, embedding, sectioning, clearing, staining, and mounting. Each of these steps has its own chemicals and their compositions must be applied strictly to avoid any distortion from what the slides should be after preparation.
When a cell dies, the first thing that must be done is the fixation. Fixation is the process taken to prevent putrefaction. The method involves soaking the tissue in chemicals known as fixatives and they include salt, Bouin's fluid, and buffered formalin. Apart from the use of chemicals, the tissue can be heated or kept inside a refrigerator. The ratio of the volumes of fixatives to the tissue should be 3:1. It is important to use more fixatives so that the tissue can be well covered.
Fixation usually introduces water that must be removed through the process called dehydration. Since alcohol and water are miscible, alcohol can be used in the process. The concentration of alcohol used should vary from low to high and in an ascending order. It is good to do it with 50%, 50%, 75%, 75%, 98%, and 98% alcohol concentrations one after the other. This is necessary to remove all bubbles and to prevent the possibility of shrinking.
The alcohol introduced into the tissue must not be left for long. The process involved in getting rid of it is known as clearing. It is done with clearing agents such as xylene, benzene, chloroform, and toluene. After this, wax is impregnated into the tissues so as to remove xylene. In addition to xylene removal, waxing makes it easy to cut the tissues and the cuts are also strong.
Dewaxing must be done in the end. In dewaxing, the tissue has to be rehydrated so as to bring it back to water. Rehydrating is done with alcohol, but this time in descending grades. You can start with 98% alcohol and stop with 50% alcohol. Of course, water will also be used in this process. The tissues are then stained with some special dyes such as Periodic Acid Schiff, Van Gieson, Masson trichrome, Sudan black, and Osmium tetroxide.
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