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.
For example, the light microscope has a lamp, the iris, diaphragm, tube with lenses, eyepiece, objective lens and adjustment knobs which of three types: condenser height, coarse and fine knobs. They all perform the function of adjusting the clarity of the slides in view.
The tissues that will be placed under the microscope must be processed before they can be used. There are different techniques to do this and they include fixation, dehydration, clearing, waxing, embedding, and staining. The use of chemicals applies in these steps and they have to be in the required amount if the tissue is going to be well prepared or last long.
Fixation is the first step to take after the death of a cell. It is done to prevent decay since tissues start breaking down immediately after death. The dead tissue is soaked in fixatives such as buffered formalin, Bouin's fluid, and salt. Other ways to prevent decay of tissues after death are refrigeration and heating. When applying fixatives, the ratio should be 3 volumes of fixatives to 1 volume of tissue. This volume must be maintained to make sure the whole tissue is 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.
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.
The slides that will be viewed should not contain wax. Thus, it should be removed by the process of rehydration. Rehydration is done with alcohol in descending grades; that is from absolute to 50 percent. Water can be reintroduced since the tissue must be brought back to water. Staining is the final process in the technique and the stains used depends on the tissue and what should be identified. They include Periodic Acid Schiff, Sudan black, Van Gieson 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.
For example, the light microscope has a lamp, the iris, diaphragm, tube with lenses, eyepiece, objective lens and adjustment knobs which of three types: condenser height, coarse and fine knobs. They all perform the function of adjusting the clarity of the slides in view.
The tissues that will be placed under the microscope must be processed before they can be used. There are different techniques to do this and they include fixation, dehydration, clearing, waxing, embedding, and staining. The use of chemicals applies in these steps and they have to be in the required amount if the tissue is going to be well prepared or last long.
Fixation is the first step to take after the death of a cell. It is done to prevent decay since tissues start breaking down immediately after death. The dead tissue is soaked in fixatives such as buffered formalin, Bouin's fluid, and salt. Other ways to prevent decay of tissues after death are refrigeration and heating. When applying fixatives, the ratio should be 3 volumes of fixatives to 1 volume of tissue. This volume must be maintained to make sure the whole tissue is 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.
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.
The slides that will be viewed should not contain wax. Thus, it should be removed by the process of rehydration. Rehydration is done with alcohol in descending grades; that is from absolute to 50 percent. Water can be reintroduced since the tissue must be brought back to water. Staining is the final process in the technique and the stains used depends on the tissue and what should be identified. They include Periodic Acid Schiff, Sudan black, Van Gieson and Osmium tetroxide.
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