Fixation And Processing

Question 1

The firs stage of tissue preparation

Answer 1

Stage1: tissue processing
1- Fixation
2- Dehydration
3- Clearing
4- Wax impregnation
5- Embedding

Question 2

The second stage of tissue preparation

Answer 2

Stage 2 tissue sectioning
1- Sectioning
2- Floating

Question 3

The third stage, of tissue prep

Answer 3

Stage 3 staining

1- Dewaxing
2- Rehydrate
3- Stain
4- Dehydrate
5- Clear
6- Mount

Question 4

What is the aim of tissue processing?

Answer 4

1- To embed the tissue in a solid medium firm enough to support the tissue and give it sufficient rigidity to enable thin sections to be cut.
2- and yet soft enough to enable the knife to cut sections with little damage to knife or tissue.

Question 5

The tissue must he subjected to what?

Answer 5

1. Completion of fixation and stopping autolysis
2. Gentle but complete dehydration – to remove aqueous fixative and any tissue water.
3. ‘Clearing’ with a substance which is totally miscible with both the dehydrating agent which precedes it, and the embedding agent which follows it.
4. Wax impregnation.
5. Embedding.

Question 6

Why must the tissue be dehydrated?

Answer 6

To remove aqueous fixative and any tissue water.

Question 7

True or false: clearing the tissue with a miscible substance

Answer 7

True

Question 8

What is fixation?

Answer 8

the rapid killing and preservation of tissue elements to retain as nearly as possible the same characteristics they had in the living body.

Question 9

What are the aims of fixation?

Answer 9

1- Prevent the process of autolysis (tissue components degradation).
2- Maintain the shape and volume during processing and staining.
3- Produce clear staining results!!
4- The tissue must be similar as possible to the original structural state with minimum loss of molecules or cells.