Why Are Controls Important?
Controls are critical for ensuring the
validity and
reliability of histological analyses. They help in confirming that the staining process, reagents, and equipment are functioning correctly. Without controls, any result obtained could be questioned, making it difficult to draw accurate conclusions.
How to Choose a Positive Control?
Selecting an appropriate positive control involves choosing a sample that is known to contain the
target antigen or demonstrate the desired reaction. This could be a tissue sample known to express a specific protein. For example, if testing for the presence of
cytokeratin in epithelial tissues, a known epithelial tissue sample should be used as a positive control.
How to Choose a Negative Control?
Negative controls are chosen based on their known lack of the target antigen or reaction. This could be a tissue sample that does not express the specific protein of interest. For instance, if you are testing for a protein specific to epithelial cells, a connective tissue sample could serve as a negative control.
Examples of Positive Controls
A few examples of positive controls include:
- A known tissue section that expresses a specific protein.
- A cell line engineered to overexpress a gene of interest.
- A sample treated with a reagent that induces a specific reaction. Examples of Negative Controls
Examples of negative controls might include:
- A tissue section known to lack the specific protein.
- A sample treated with a
non-reactive reagent.
- A
blank slide with no tissue section for background staining assessment.
How to Implement Controls in Your Experiments?
To implement controls in your experiments, follow these steps:
- Identify the specific antigen or reaction you are testing for.
- Select known positive and negative control samples.
- Process the control samples alongside your experimental samples.
- Compare the results of your experimental samples to the controls to validate your findings.
Conclusion
Positive and negative controls are indispensable in histology for ensuring the accuracy and reliability of results. They help in verifying that the staining procedures, reagents, and equipment are functioning correctly and provide a reference point for interpreting the outcomes of experiments or diagnostic tests. By carefully selecting and implementing appropriate controls, histologists can significantly reduce the risk of erroneous results and improve the validity of their findings.
