INTRO TO HISTOLOGY- Processing of Tissues and Cells

Question 1

what is Histology

Answer 1

histology is the scientific study of the cells and tissues on a microscopic level.

Question 2

What is Histopathology

Answer 2

This studies and diagnoses the diseases of tissues

Question 3

What is Cytology

Answer 3

This is the study of the cells

Question 4

What is Cytopathology

Answer 4

Is the study and diagnosis of diseases on a cellular level.

Question 5

What is the purpose of histology

Answer 5

it examines the correlation between function and structure in cells and tissues

Question 6

what are the 2 ways cell samples are taken?

Answer 6

• They are taken through exfoliation/ brushing scraping.

- Or through aspiration which is where a fine needle will take a sample from the affected area

Question 7

What is the overall process of preparing a tissue sample in histology (5 steps)

Answer 7

1. Cutting specific areas of tissue
2. `Fixation
3. Dehydration
4. Clearing
5. Wax infiltration

Question 8

How does a fixative/ fixation help the tissue be ready for examination? think of stability

Answer 8

Stability:

• makes sample insoluble as the proteins nucleic acid and mucopolysaccharides will be stabilized
• hardens the sample
• makes it stay in a life-like condition.

Question 9

How does a fixative/ fixation help the tissue be ready for examination? think of decay
and staining

Answer 9

• halts bacteria putrefaction
  (decay)
• halts enzyme autolysis
  (self-digestion of itself)
• enhances later staining technique

Question 10

What chemical fixatives can be used in fixation?

think 2 aldehydes
think 3 oxygen containing compounds

Answer 10

• 10% buffered formalin
• glutaraldehyde
• osium tetraoxide OsO4
• potasssium dichromate K2Cr2O7
• ethanol C2H5OH

Question 11

What PHYSICAL fixatives can be used in fixation?

Answer 11

• microwave fixation

- vapors/ airdrying

Question 12

What fixative is used for cells - cytology-

Answer 12

Canory’s fixative

Question 13

Why is dehyration needed in the process of preparing the tissue sample

Answer 13

This is so that the fixative and water is removed as these are immiscible with the medium used in later processing

Question 14

What can be used to dehydrate the tissue sample? give 3 examples
and what is the method?

Answer 14

• alcohol will dry out the water and fixative.
• ethanol methanol and acetone.
• It is done by gradually increasing alcohol concentrations 10% 20% 50% 95% and 100%

Question 15

What is the process of clearing and why does it need to be used in this process

Answer 15

Clearing is used to remove the dehydrating fluid from the tissue sample as alcohol is also immiscible with the wax/ embedding media

Question 16

What is the most popular use of a clearing agent.

Answer 16

Xylene.

Question 17

What other clearing agent can be used?

Answer 17

Chloroform, Petrol, Benzene, Toluene

Question 18

Once the clearing agent has been used to remove the dehydrating fluid (alcohol)
WAX INFILTRATION can now occur.. what is wax infiltration

Answer 18

This is where the tissue sample is put into a mould as is immersed into the wax more specifically paraffin wax

Question 19

Why is wax used in this process

Answer 19

Wax

• improves ribonning
• increases hardness
• decareses melting point

Question 20

After the process of wax infiltration a T____ B___ is made and now ready to be cut

Answer 20

Tissue blocks are made after the immersion of the tissue block in wax

Question 21

what is the T____ B____’s then cut with

Answer 21

The tissue blocks are cut by a microtome