the study of changes in tissues caused by disease.
the study of changes in cells caused by disease.
Question 2
Question
Select Three hazards associated with working in a Histopathology laboratory.
Answer
- Chemical: fixatives, stains, chemicals
– Biological: cross infection
– Physical: sharps, radiation
- Safety: slips, trips, falls
Question 3
Question
Explain what a fixative does
Answer
preservation of tissue specimen
decontaminates all viruses associated with the tissue specimen
Question 4
Question
List Six features of an ideal fixative
Answer
• Will not swell or shrink tissue
• Is economical
• Has convenient shelf life and storage
• Will be safe for user and environment
• Will preserve tissue in life like manner
• Will not add artefact material to tissue
• Will add artefact material to tissue
Question 5
Question
Select Three fixative/s that can be used for Cytology smears?
Answer
Spray fixed with aerosol of propanol and acetone+ Poly ethylene glycol- a water soluble wax
Methanol
Ethanol
Xylene
Sodium dihydrogen phosphate monohydrate 4g
Question 6
Question
Select Three physical agents that can be used to assist in the fixation of tissues.
Answer
Microwave
Heat
Ultrasound
Freeze
Question 7
Question
True or false: autolysis represents the changes to tissue that occur before fixation due to bacterial contamination.
Answer
True
False
Question 8
Question
What type of fixative is Neutral Buffered Formalin classed as?
Answer
Universal fixative
Fixative used for specific purposes
Question 9
Question
Why is Formalin Buffered to a neutral pH?
Answer
because the further a fixative is from the pH of body tissues the more distortion you can get in the tissue at the cellular level.
because the further a fixative is from the pH of body tissues the less distortion you can get in the tissue at the cellular level.
Question 10
Question
What is the function of xylene in tissue processing?
Answer
To cut sections, the tissue has to be embedded in paraffin wax, but wax is not soluble in water or alcohol. However, it is soluble in a paraffin solvent called 'xylene'.
Cleaning up the lab station to prevent contamination of other specimens and users of the facilities
Question 11
Question
Why is the histological section cut to approximately 5µm thick?
Answer
- Sample needs to be thin enough for light microscopy (about 1 cell layer thick)
- makes it easier to evaluate tissue and look at its morphology
- Provides enough thickness to account for cell to cell ratio
Question 12
Question
List method/s used for the collection of Cytology samples.
Answer
- Pap Smears, Endoscopy samples, some FNA (fine needle aspiration) specimens
- Blood test, saliva test, sputum collection
Question 13
Question
Give an example of a Chemical Fixative that belongs to Aldehydes
Answer
- Formaldehyde, Glutaraldehyde
- Ethanol, Methanol
Question 14
Question
Give an example of a Chemical Fixative that belongs to Oxidising agents
Answer
- Osmium tetroxide, Potassium Dichromate
- Ethanol, Methanol
Question 15
Question
Give an example of a Chemical Fixative that belongs to Protein coagulants
Answer
- Ethanol, Methanol
- Mercuric Chloride, Picric acid
Question 16
Question
Give an example of a Chemical Fixative that belongs to Uncertain mechanism