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.
The microscopes used are of various types. The students are taught how to view with the light, electron, phase contrast, fluoresce, confocal microscope and others. Some of these are more preferred to others based on the size of the slides and how clear you want it to become. They also differ in various ways.
Components of a light microscope include lamp, diaphragm, tube, eyepiece lens, objective lens, and knobs. The adjustment knobs are of three types and they are used to change the clarity of the slide in view. They are fine knob, coarse knob, and condenser height.
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 the cell dies, it is going to start decaying almost immediately but this can be avoided by fixation. Fixation is therefore a step taken to prevent putrefaction so that the tissue can still be useful. Fixatives to use for this purpose include Bouin's fluid, salt, and buffered formalin while alternative methods are refrigeration and heating. When fixatives are used, the volume should be in the proportion of 75 percent to 25 percent. The quantity of the fixative should be more than the tissue so that it can be well soaked.
Dehydration follows after fixation. After fixing, water has to be removed and this can be achieved by using alcohol. However, you should make sure that you use different grades of alcohol in ascending order. The formula, 50%, 50%, 75%, 75%, 98%, and 98% is ideal. The gradual ascent should be followed to remove all bubbles and prevent shrinking due to distortion.
After dehydrating the tissue, the alcohol has to be removed and this can be done by the process called clearing. It can be done with clearing agents such as xylene, benzene, toluene, and chloroform. Afterward, impregnate with wax to remove xylene. Apart from removing the xylene, waxing makes cutting easy and the quality of the cuts to be 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.
The microscopes used are of various types. The students are taught how to view with the light, electron, phase contrast, fluoresce, confocal microscope and others. Some of these are more preferred to others based on the size of the slides and how clear you want it to become. They also differ in various ways.
Components of a light microscope include lamp, diaphragm, tube, eyepiece lens, objective lens, and knobs. The adjustment knobs are of three types and they are used to change the clarity of the slide in view. They are fine knob, coarse knob, and condenser height.
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 the cell dies, it is going to start decaying almost immediately but this can be avoided by fixation. Fixation is therefore a step taken to prevent putrefaction so that the tissue can still be useful. Fixatives to use for this purpose include Bouin's fluid, salt, and buffered formalin while alternative methods are refrigeration and heating. When fixatives are used, the volume should be in the proportion of 75 percent to 25 percent. The quantity of the fixative should be more than the tissue so that it can be well soaked.
Dehydration follows after fixation. After fixing, water has to be removed and this can be achieved by using alcohol. However, you should make sure that you use different grades of alcohol in ascending order. The formula, 50%, 50%, 75%, 75%, 98%, and 98% is ideal. The gradual ascent should be followed to remove all bubbles and prevent shrinking due to distortion.
After dehydrating the tissue, the alcohol has to be removed and this can be done by the process called clearing. It can be done with clearing agents such as xylene, benzene, toluene, and chloroform. Afterward, impregnate with wax to remove xylene. Apart from removing the xylene, waxing makes cutting easy and the quality of the cuts to be 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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