Erythrocytes, or red blood cells, are the most ubiquitous cells in a blood smear. They appear as biconcave discs of uniform shape and size that lack organelles and granules. The central pale area of each red blood cell is due to the concavity of the disc.
Neutrophils. Neutrophils are the commonest type of white blood cell found in a blood smear. They make up 60-70% of the total amount of white blood cells.
A blood smear looks for the numbers and characteristics of the three types of blood cells: Red blood cells (RBCs) are the cells that transport oxygen to the tissues. White blood cells (WBCs) are cells that fight infection among several other functions.
The identification of blood cells is based primarily on observations of the presence or absence of a nucleus and cytoplasmic granules. Other helpful features are cell size, nuclear size and shape, chromatin appearance, and cytoplasmic staining.
When viewed under the microscope, the smear will show different types of leukocytes as well as red cells. Students will be able to differentiate white blood cells based on their shape and nucleus. * Neutrophils are often first responders during infection. Death of many neutrophils form pus.
Complete blood count and peripheral blood smearChanges in the numbers and the appearance of different types of blood cells often help diagnose leukemia.
How to use a microscope
- Move the stage (the flat ledge the slide sits on) down to its lowest position.
- Place the glass slide onto the stage.
- Select the lowest power objective lens.
- Turn the coarse focus knob slowly until you are able to see the cells.
In order to see bacteria, you will need to view them under the magnification of a microscopes as bacteria are too small to be observed by the naked eye. At high magnification*, the bacterial cells will float in and out of focus, especially if the layer of water between the cover glass and the slide is too thick.
Drop of blood too large or too small. Spreader slide pushed across the horizontal slide in a jerky manner. Failure to keep the entire edge of the spreader slide against the horizontal slide while making the smear. Failure in using appropriate angle for the spreader slide.
Commonly used stain in our environment is Leishman stain which is composed of polychrome methylene blue (basic component) and eosin (acidic component). May-Grunwald Giemsa or Wright-Giemsa stain can also be used.
Based on our experience and a review of the literature on performance evaluation of currently available analyzers, we suggest that the criteria for a blood smear scan should include (a) CBC and/or DIFF results flagged by the automated analyzers for verification, (b) initial platelet count below 100×109/L, whether
Fingerprints, oil, water, and detergents will cause holes to form within the blood smear.
Concentration and freshness of reagents may affect the quality of the stain. Washing and drying of the smear between steps should be consistent. Excess water left on the slide will dilute reagents, particularly Gram's iodine.
It consists of a mixture of eosin (an acidic stain), and methylene blue (a basic stain) in alcohol and is usually diluted and buffered before use. It stains the different components of blood in a range of shades between red and blue. The similar Wright's stain is favoured by American workers.
What is Cellular Staining? Cell staining is a technique that can be used to better visualize cells and cell components under a microscope. By using different stains, one can preferentially stain certain cell components, such as a nucleus or a cell wall, or the entire cell.
This area of the smear is usually scanned at low power to identify low numbers of potentially diagnostic cells (e.g. blasts in a leukemia), infectious agents (e.g. trypanosomes, microfilaria), and certain RBC changes (hypochromasia, agglutinates).
Why are thick or dense smears less likely to provide a good smear preparation for microscopic evaluation? It will diminish the amount of light that can pass through making it difficult to visualize the morphology of single cells under the microscope. Some times the stain can't penetrate all of the bacteria.
A blood smear is often used as a follow-up test to abnormal results on a complete blood count (CBC) to evaluate the different types of blood cells. It may be used to help diagnose and/or monitor numerous conditions that affect blood cell populations.
The blood smear is a quick test. Your doctor may draw blood from your arm or by pricking your finger. You usually get the results in one to two days.
A complete blood count (CBC) gives important information about the kinds and numbers of cells in the blood, especially red blood cells, white blood cells, and platelets. A CBC helps your doctor check any symptoms that you may have, such as weakness, fatigue, or bruising.
CBC is the most useful initial laboratory test in patients suspected of having leukemia. Most patients will show some abnormality in the CBC and some blasts will be seen in the peripheral smear in patients with acute leukemias. To diagnose CLL, a lymphocytosis of greater than 5000/mm3 must be present.
