Session 1-Intro Flashcards
What is disease?
Pathological condition of a body part, organ or system, characterised by an identifiable group of signs of symptoms
What is pathology?
Study of disease and cellular dysfunction
What is the importance of a microscopic diagnosis?
Definitive and is used before major surgery to remove a lesion
True or false: histology is faster and cheaper than cytology
FALSE - other way round
Where can serous carcinoma be found? (5)
1) ovary
2) Fallopian tube
3) uterus
4) cervix
5) peritoneum
What is tissue autolysis?
Self-digestion, begins when the blood supply is cut off
How can the biochemical process of autolysis be blocked?
Fixatives
What do fixatives do? (3)
1) inactivate tissue enzymes and denature proteins
2) prevent bacterial growth
3) harden tissue
Which chemical is used in fixation?
Formalin (formaldehyde in water)
How long does fixation take?
24-48 hours
How can the tissue be made hard enough to be able to take very thin slices?
Paraffin wax is used. Water has to be removed first:
- Dehydration using alcohol
- Replace alcohol with xylene which mixes with wax
- Replace xylene wth molten paraffin wax
What is used to cut very thin sections of tissue?
Microtome
What is used to stain the tissue?
Haematoxylin and Eosin (H&E)
What does haematoxylin stain?
Nuclei purple
What does eosin stain?
Cytoplasm and CT pink
What is immunohistochemistry?
Demonstrates substances in/on cells by labelling them with specific antibodies
What happens in immunohistochemistry?
Antibody is joined to an enzyme that catalyses a colour-producing reaction (usually brown)
Which substances can be demonstrated in immunohistochemistry? (5)
Antigenic substances:
1) actin-identifies smooth muscle
2) cadherins-cell adhesion molecules, deficient in some carcinomas
3) hormone receptors eg ER, PR
4) Her2 receptor-growth factor receptor, predicts response of breast cancer to Herceptin
5) microorganisms
What are cytokeratins?
Family of intracellular fibrous proteins present in all epithelia
What are cytokeratins a marker for?
Epithelial differentiation
What can cytokeratins give information about?
Primary site of carcinoma
What does molecular pathology study?
How diseases are caused by alterations in normal cellular molecular biology
What do in situ molecular tests show?
How DNA is altered in tissues prepared for microscopy eg FISH
What can the sequencing of DNA purified from tumour tissue show?
If mutation is present in a particular gene
Why aren’t frozen sections used often?
Morphology is not as good as in paraffin sections and accuracy is ~96%
