Wet mounts are suitable for studying water-bound organisms such as paramecium or bodily fluids such as saliva, blood and urine. In a section mount, an extremely thin cross-section of a specimen is used. Using a microtome, cut a thin slice of your selected specimen such as an onion, and carefully set it on your slide. Then follow the instructions for a dry or wet mount. A stain can often be applied directly to the specimen before covering with a cover slip.
Section mounts are suitable for useful for a wide variety of samples such as fruit, vegetables and other solids that can be cut into small slices. A smear is made by carefully smearing a thin layer of the specimen across a slide and then applying a cover slip.
Typically, a smear should be allowed to air dry before applying a stain. Stains are used to help identify different types of cells using light microscopes.
They give the image more contrast and allow cells to be classified according to their shape morphology. By using a variety of different stains, you can selectively stain different areas such as a cell wall, nucleus, or the entire cell. Stains can also help differentiate between living or dead cells. Stains tend to be grouped as neutral, acidic or basic, depending upon their chemical makeup and will attract or repel different organisms accordingly. For example, scientists and health professionals use Methylene Blue, a slightly alkaline stain, to reveal the presence of deoxyribonucleic acid, more commonly known as DNA.
Methylene Blue is an alkaline stain useful in identifying acidic cell nuclei and DNA in animal, bacteria or blood samples. Eosin Y is an acidic stain which stains pink for alkaline cells cytoplasm, for example.
It colors red for blood cells, cytoplasm and cell membranes. Eosin's most important medical uses are in blood and bone-marrow testing, including the PAP smear.
Place a piece of napkin or paper towel against the opposite side of your cover slip, right up against the edge. This will help draw the stain under the cover and across the specimen. Get it into the holder as soon as possible. When ordering a specimen in the computer please be sure to select the correct specimen type or else it cannot be processed. Surgical Pathology : A specimen is ordered as a "surgical pathology" specimen when a core biopsy has been obtained. Even if slides are made and a cytojar is used along with the core biopsy, it is still ordered as a surgical pathology.
Examples of surgical pathology specimens include lung, liver, and GI biopsies collected in formalin, with a needle wash in a cytojar and smears made.
Cytology : A specimen is ordered as a "cytology" when no core biopsy has been obtained. This is when the aspirate is used to make cytology smears and placed in the cytojar ONLY. Examples of cytology specimens include fine needle aspirations of thyroid, pancreas, cysts etc. Proper fixation is essential when it comes to analyzing cytology specimens. If a specimen is not collected appropriately, the diagnosis is compromised.
The goal of the laboratory is to provide quality patient care and by following these tips we can decrease the number of "indeterminant" diagnoses. Body fluids CSF, pleural effusion, peritoneal effusion, urine, cyst fluid etc.
It is important that the specimens be sent to the laboratory as soon after collection as possible. In some cases it is not possible to get the specimen down to the lab immediately, but there are other things that can be done to preserve cellular detail.
If a biohazard fridge is available, refrigerate the specimen until delivering it to the lab. If cytolyt solution is available add an equal amount of cytolyt solution to the specimen. If pre-filled cytojars are available they can also be used. If a specimen is being split amongst various departments it is safer not to add cytolyt because this can inhibit testing in certain instruments in other areas of the laboratory. Inquire with the other laboratory departments if they can process specimens that are fixed with cytolyt solution.
Histochemical stains typically hematoxylin and eosin are therefore used to provide contrast to tissue sections, making tissue structures more visible and easier to evaluate. Following staining, a coverslip is mounted over the tissue specimen on the slide, using optical grade glue, to help protect the specimen. While histology is great for lower resolution imaging of whole tissues, it is limiting if you want to investigate subcellular structures for example when studying changes in brain tumors.
In this case, a more detailed and high-powered technique such as brain cancer electron microscopy is required. If histology has enough resolution for your needs, do you prefer to make your own slides, or send tissues to a histology lab for processing? Leave a comment below. Want to know more about histology? Visit the Bitesize Bio Histology Hub for tips and tricks for all your histology experiments.
If you found this article useful, you might want to check out some of our related articles below:. Originally published April 4, Reviewed and updated on November 19, Has this helped you? Then please share with your network. Facebook Twitter LinkedIn More. Written by Nicola Parry.
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