Histopathology Flashcards
What is used in medical histopathology?
Any material used in diagnostic purpose; e.g. Appendix, Colon, Body Fluids, etc…
How is human disease histologically identified?
Identifying abnormailities within a histopathological sample is done via testing biospys, fluid samples, etc…
How might histopatholigical samples be dealt with?
- Preserve; against autolysis & putrefaction
- Select; what will be useful in investigation
- Identify; what is wrong
How is a sample fixed?
Samples are typically fixed using formalin
What does fixation do?
Preserves tissues and organic matter in a life-like condition to prevent decay.
Define; Autolysis & Putrefaction?
Autolysis; enzymatic digestion of cells by the action of its own enzymes.
Putrefaction; process of decay in a body.
What is formaldehyde?
Formaldehyde is carcinogenic to the body but useful in histopathology; it holds proteins in shape and denatures them preventing decay.
What is formalin?
Formalin is a 10% neutral buffer. Its made from water and formaldehyde and used to fix samples.
Outline the process of specimen dissection.
- Area of interest; area of suspicion (e.g. tumor)
- Clearance margins; margins cut around a tumor to ensure no cancerous cells are present
- Depth; depth of invasion of a cancer, indicating the progression of the cancer
- Pleomorphic tumor; differntiating parts of cancerous tumors(not uniform)
- Normal tissue; base tissuing outlining the healthy
How are pathological speciemens processed?
Samples are cast into paraffin wax.
What dyes are used in basic histological stains?
Haematoxylin & Eosin Y
What does Haematoxylin stain?
Stains cell nucleus blue
What does Eosin Y stain?
Stains eosinphilic tissue pink
Name 3 histopatholgical sample special stains used in morphology.
Collagen; stained pink.
Hepatitis; Orcein stain is used to pick up the hepatitis B surface antigens.
Haemosiderin; Pearl stains are used here to pick up any traces of iron.
What are the 3 stains for Micro-organisms?
Gram
Ziehl-Neelson
Grocott
What does a Gram stain do?
Only determines whether bacterium is present(purple) or absent(pink).
What does a Ziehl-Neelson stain do?
Identifies myobacterium present within sample; blue = normal, red = infection
What does a Grocott stain do?
Identifies presence of fungi; fungal infection
Why are samples cast into paraffin wax?
In order to obtain thingly sliced sections of samples for observation.
Why is the processing of histipathological samples reversed?
When attempting to stain a sample cast in paraffin wax the water-based stain will not work properly since wax is made of oil. The reverse is done to extract the oil.
