What would probably happen if you forgot to heat fix the smear before staining?
Heat-fixing the slide fixes the bacteria to the slide surface. If this step is not done, the bacteria in the smear would be washed off of the slide during the staining and decolorization steps. You would not see anything on the slide under the microscope.
Why is it necessary to add stain to a smear?
The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.
Why is time an important factor in simple staining?
Why is time an important factor in simple staining? Time is important because it creates a contrast between the bacteria and the stain. If you over or under stain you won't be able to see bacteria.
What could affect the quality of a smear?
If the smear is overheated during heat fixing, the cell walls will rupture. 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.
Why is it important to smear the blood as soon as the drop is placed on the slide?
Common Causes of a Poor Blood Smear • As soon as the drop of blood is placed on the glass slide, there should be no delay in the making of the smear. Any delay, whatsoever, results in abnormal distribution of the white cells with many of the white cells accumulating at the thin edge of the smear.
What problems arise from forgetting to clean your slide at the beginning of the smear process?
What problems arise from forgetting to clean your slide at the beginning of the smear process? 1. Bacteria will attach to the grease or dirt and wash away when staining.
What are the common mistakes in preparing bacterial smear?
Terms in this set (8)
- Applying too much bacteria to the slide.
- Not heat fixing the bacteria before staining.
- Wiping off the slides will result in a loss of bacteria present.
Why is it important to limit the quantity of cells on a smear?
why is it important to limit the quantity of cells used to prepare a smear? large amounts of cells in a smear can cause staining artifacts because stain is not washed away by destaining agents or water.
What is the disadvantage of having a really thick smear when staining?
Do NOT make your smear suspensions too thick. The dye will not penetrate well, and there will be far too many bacterial cells to see individual shapes and arrangements.
Why is it important to smear the blood as soon as the drop is placed on the slide quizlet?
Why is it important to smear the blood as soon as the drop is placed on the slide? A delay results in abnormal distribution of WBCs, with larger cells accumulating at the thin edge.
Why it is necessary that blood smears should be prepared without delay?
Preparing Blood Smears If you are using venous blood, blood smears should be prepared as soon as possible after collection (delay can result in changes in parasite morphology and staining characteristics).
What are two common mistakes when making a bacterial smear for staining?
Match
- Applying too much bacteria to the slide.
- Not heat fixing the bacteria before staining.
- Wiping off the slides will result in a loss of bacteria present.
What are the common errors in staining procedure?
The rank of errors is:
- Over decolourisation.
- Mixed cultures.
- Misread stains.
- Aged subcultures.
- Disorganisation.
- Inadequate fixation and Insufficient culture.
Sep 27, 2020
What are the potential consequences of making a smear that is too thick?
Insufficiently dried smears (and/or smears that are too thick) can detach from the slides during staining. The risk is increased in smears made with anticoagulated blood. At room temperature, drying can take several hours; 30 minutes is the minimum; in the latter case, handle the smear very delicately during staining.
Is it important that the smear is thick in order to ensure that the stain will be retained on the slide?
Water is applied to the slide before emulsifying cells from a solid medium. It is important that the smear is thick in order to ensure that the stain will be retained on the slide.
Why is it important to fix the thin smears and not thick smear?
Thick smears The blood elements (including parasites, if any) are more concentrated (app. 30×) than in an equal area of a thin smear. Thus, thick smears allow a more efficient detection of parasites (increased sensitivity).
What are the common errors in making a thick and thin blood film?
Blood smears – common errors
- slide 1 – perfect smear.
- slide 2 – smear technique interrupted in middle.
- slide 3 – smear was skewed.
- slide 4 – blood droplet too thick.
- slide 5 – smear too short.
May 2, 2017
Why is it important to smear blood as soon as the drop is placed on the slide?
Common Causes of a Poor Blood Smear • As soon as the drop of blood is placed on the glass slide, there should be no delay in the making of the smear. Any delay, whatsoever, results in abnormal distribution of the white cells with many of the white cells accumulating at the thin edge of the smear.
What are the possible errors encountered in peripheral blood smear preparation?
Terms in this set (6)
- too long or too thin. spread slide angle too low. …
- too short or too thick. spreader slide angle too high. …
- waves or ridges. hesitation while pushing spreader slide. …
- holes in smear. dirty slide. …
- abnormal cell morphology/artifacts. improper drying of smear. …
- uneven cell distribution.
What can cause false results in Gram staining?
False-negative Gram stains could occur due to inadequate specimen or smear preparation or failure to examine an adequate number of fields. In addition, training and maintenance of proficiency for Gram staining remain challenging (5, 20).
What is the most common source of errors during the Gram stain procedure?
In this study, we present a review of over 6,000 Gram-stains and establish an error rate of around 3%, with the most common reason for error being an over-decolourisation step resulting in organisms that should be Gram-positive appearing as Gram-negative.
How can the thickness of the smear affect the staining procedure?
How can the thickness of the smear affect the staining procedure? If it is too thick it won't stain properly. The stain will not get to the lower layers and clumps of cells may not be decolorized.
What happens to a blood smear if it is too thick?
Insufficiently dried smears (and/or smears that are too thick) can detach from the slides during staining. The risk is increased in smears made with anticoagulated blood. At room temperature, drying can take several hours; 30 minutes is the minimum; in the latter case, handle the smear very delicately during staining.
Why is it important to fix the thin smears and not the thick smear?
6. Thick smears are mainly used to detect infection and to estimate parasitemia. Thin smears allow the examiner to identify malaria species, quantify parasitemia, and recognize parasite forms like schizonts and gametocytes.
Why is it important to smear the blood on the slide as soon as the blood drop is placed?
Common Causes of a Poor Blood Smear • As soon as the drop of blood is placed on the glass slide, there should be no delay in the making of the smear. Any delay, whatsoever, results in abnormal distribution of the white cells with many of the white cells accumulating at the thin edge of the smear.
What happens if gram-negative cells are Decolorized too long?
The decolorizer should stay on the slide for no more than 15 seconds! If the decolorizer is left on too long, even gram positive cells will lose the crystal violet and will stain red. The staining procedure is here.
Why might Gram staining fail sometimes?
Gram-positive bacteria may lose their ability to retain crystal violet and stain Gram negatively for the following reasons: Cell wall damage of bacteria due to antibiotic therapy or excessive heat fixation of the smear. Over- decolorization of the smear.
What might happen if a smear is too thick?
Smears that are too thick will be difficult to decolorize and imposable to read. Do not cover the entire slide with the sample. This will make handling difficult and areas may be missed during decolorization. An area the size of a nickel usually is adequate.
What are the common errors in staining methods?
The rank of errors is:
- Over decolourisation.
- Mixed cultures.
- Misread stains.
- Aged subcultures.
- Disorganisation.
- Inadequate fixation and Insufficient culture.
Sep 27, 2020
What are sources of error in Gram staining?
Sources of Error For example, the Gram stain will not detect organisms that exist within host cells (such as Chlamydia), organisms with no cell wall (such as Mycoplasma, Ureaplasma, and Rickettsia), and bacteria that are too small to be seen with light microscopy (such as Treponema).