University students studying some medical science related courses usually have some of their lectures in the histology lab. There, they are given microscopes and tissues prepared and preserved so that they can identify them under a microscope. Before these microscope slides are given to them, the technologists perform some histology techniques. It is important to know them as a student because they can also form exam questions.
There are different types of microscopes used in the lab. They include the light, electron, fluoresce, phase contrast and confocal microscopes. The one to use depends on the slides to view and how requirements available for using them. These microscopes are also different in several ways.
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.
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.
After fixing, the next step is dehydration. The essence of dehydrating is to remove water from the tissue. To do this, alcohol is used in ascending grades. That is, you can use 50%, 50%, 75%, 75%, 98% and 98% in that order. Maintaining this gradual ascent is important. When dehydration is not done properly, it can cause bubbles to exist and the tissue can distort after shrinking.
The next step after dehydration is clearing. Clearing is the process by which the alcohol that was used in dehydration is now removed. Some clearing agents include benzene, toluene, chloroform and xylene. Wax is then introduced to remove the clearing agents. Wax is preferred because it also makes the tissues to be cut without stress.
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 types of microscopes used in the lab. They include the light, electron, fluoresce, phase contrast and confocal microscopes. The one to use depends on the slides to view and how requirements available for using them. These microscopes are also different in several ways.
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.
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.
After fixing, the next step is dehydration. The essence of dehydrating is to remove water from the tissue. To do this, alcohol is used in ascending grades. That is, you can use 50%, 50%, 75%, 75%, 98% and 98% in that order. Maintaining this gradual ascent is important. When dehydration is not done properly, it can cause bubbles to exist and the tissue can distort after shrinking.
The next step after dehydration is clearing. Clearing is the process by which the alcohol that was used in dehydration is now removed. Some clearing agents include benzene, toluene, chloroform and xylene. Wax is then introduced to remove the clearing agents. Wax is preferred because it also makes the tissues to be cut without stress.
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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