Histology

Question 1

State the stages of basic histological technique

Answer 1

1.Fixing
2. embedding
3. sectioning/slicing
5. staining

Question 2

explain first stage of the basic histological technique

Answer 2

fixing
tissue collected by biopsy’s
1. then use chemical process to stabilise proteins in tissue
2. solution of formaldehyde causing proteins in tissue to link together (now cross linked)
3. stabilising structural integrity and makes non-functional protein you stop enzyme activity
4. also inactivates most pathogens e.g., Bacteria and viruses

Question 3

explain the 2nd stage of the basic histological technique

Answer 3

Embedding
Often within paraffin wax or resin further stabilises tissue
1. prevent tissue tearing or distorting when sectioned
2. embedding medium soaks into tissue filling spaces inside and between cells and extracellular structures
3. provides mechanical support
4. could also use rapid freezing stops need for fixation and embedding

Question 4

What is rapid freezing?

Answer 4

stops the need for first two stages of histology - fixation and embedding

Question 5

Explain the third stage of the basic histology technique

Answer 5

sectioning
1. use microtome – tissue slicing machine
2. thin slices as light pass through to see structural detail
3. slices mounted on glass microscope slide

Question 6

Explain the 4th adn final stage of the basic histology technique

Answer 6

staining
Also dehydrate and clear.
1. Remove embedding medium using chemical solvent
2. Removing water increases clarity removed by exposing to other solvent like ethanol of acetone water then solvent evaporates leaving sample dry
3. Tissue mounted in clearing medium – effecting ability to image tissue
4. Media has similar reflective index to many proteins in tissue e.g., orange oil so proteins are invisible and only tissue stains are visible