Questions and Answers
What is the primary purpose of fixation in histopathology?
The pH level for fixation must be lower than 6 to prevent excessive acidity.
False
What is the term used to describe the microscopic examination of tissues to study disease manifestations?
Histopathology
The volume of the fixative should be __________ times the volume of the tissue to be fixed.
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Match the steps of tissue processing with their descriptions:
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Which temperature is suitable for rapid fixation of surgical specimens?
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Hydrogen ion concentration does not affect fixation processes.
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Name one buffer that can be used in the fixative to maintain pH.
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Study Notes
Histopathologic Techniques
- Involves preparing tissues for microscopic examination.
- Histopathology examines tissue to study disease manifestations.
Factors Affecting Fixation
- Volume of Fixative: Should be 10-20 times greater than the volume of the tissue being fixed.
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Hydrogen Ion Concentration (pH): Must range from 6 to 8 to prevent excessive acidity.
- Hypoxia can lower tissue pH; buffering in fixatives is necessary.
- Excessive acidity can cause the formation of formalin-heme pigment, resulting in black, polarized deposits in tissues.
- Recommended buffers: phosphates, bicarbonate, cacodylate, veronal.
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Temperature:
- Room Temperature (RT) fixation using formalin is standard.
- Formalin at 60°C can facilitate rapid fixation for urgent biopsy specimens.
- Formalin at 100°C is useful for fixing tissues infected with tuberculosis.
Steps in Tissue Processing
- Fixation: Most critical step; prevents autolysis and putrefaction, preserves tissue near its living state.
- Dehydration: Removing water content from tissues.
- Clearing: Preparing tissue to transition from alcohol to paraffin.
- Infiltration: Impregnation of tissue with a medium (usually paraffin).
- Embedding: Involves retaining the infiltrated tissue in a solid medium.
- Trimming: Preparing the block for sectioning.
- Sectioning: Cutting thin slices of the embedded tissue for examination.
- Staining: Applying dyes to enhance visualization of tissue components.
- Mounting: Placing stained sections on slides for observation.
- Labeling: Identifying slides for future reference.
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Description
Explore the essential histopathologic techniques and the factors influencing fixation in tissue preparation for microscopic analysis. This quiz targets key concepts covered in Chapter 2 of the General Path, Histopath, and Cytopathology course for BSMT-3A students.
