L1 ANATOMY LAB INTRO

Question 1

What is Histology?

Answer 1

Study of the microanatomy of cells, tissues and organs and their structure.

Question 2

What is Histopathology?

Answer 2

Study of tissues affected by disease.

Question 3

What are the 10 steps involved in the production of Histological slides.

Answer 3

1. Obtain fresh specimen
2. Fixation
3. Dehydration
4. Clearing
5. Wax Filtration
6. Embedding
7. Sectioning
8. Staining
9. Slide mounting
10. View slide

Question 4

What does obtaining a fresh specimen involve?

Answer 4

Obtained from various sources, cut into 3 mm squares to facilitate fixation.

Question 5

What does fixation involve?

Answer 5

Fixation serves to retain the structure of the tissue and limit microbial growth that could otherwise make analysis more difficult or result in artefacts

Question 6

What does dehydration involve?

Answer 6

The tissue is progressively dehydrated by immersing it in successively higher concentrations of alcohol before transfer to an organic solvent (e.g. xylene) and finally embedding in wax.

Question 7

What does clearing involve?

Answer 7

This involves immersing the tissue in an organic solvent like xylene to prepare it for wax infiltration.

Question 8

What does wax infiltration involve?

Answer 8

The most commonly used wax for infiltration is paraffin wax. Xylene is replaced with molten wax (60°C), which infiltrates the tissue. The tissues are immersed in a wax bath.

Question 9

What does embedding involve?

Answer 9

• Immersing the tissue in a molten medium which is paraffin wax, which is then enclosed by a mould. This medium then solidifies to form a block.

Question 10

What does sectioning involve?

Answer 10

Tissues are sectioned using a microtome of 3–5 μm thickness

Cryostat: cuts sections from deep-frozen blocks, usually of unfixed tissue.

Question 11

What does staining involve?

Answer 11

Most commonly used diagnostic stain for histology is haematoxylin and eosin, often referred to as ‘H&E’ staining. Typically, nuclei are stained blue, whereas the cytoplasm and extracellular matrix are stained varying shades of pink.
Slides are then dehydrated through an ascending series of alcohol, passed through an organic solvent (xylene) and covered with a coverslip to obtain a permanent preservation and retention of the specimen

Question 12

What are the steps in using a light microscope?

Answer 12

1. Switch on power supply to microscope. Clean slide to be viewed with lens paper and place in slide holder section of microscope.
2. Centre the slide so the tissue section is directly above the aperture.
3. Use the Coarse adjustment knob to bring the stage all the way up until it can go no further. Turn objective lens to the lowest magnification which is usually x4.
4. Use the fine adjustment knob to obtain a clear focus. 5.Once the slide is focused at low magnification, then switch to next magnification (*10) and adjust the fine focus knob.