Tissue Processing

Question 1

To study tissues, one must
prepare thin and translucent
histological sections or
tissue slices that can be
studied with the aid of a ______

Answer 1

microscope

Question 2

In order to make a histology
slide, the tissue specimen
undergoes various steps of
_________

Answer 2

tissue processing

Question 3

STEPS IN TISSUE PROCESSING

Answer 3

1. Fixation
2. Decalcification
3. Dehydration
4. Clearing
5. Infiltration
6. Embedding
7. Cutting
8. Sectioning
9. Sectioning
10. Mounting

Question 4

Since cellular decomposition begins immediately after the death of a human/patient, tissues must be ______ to
prevent alterations in their structure caused by decomposition.

Answer 4

fixed

Question 5

After the specimen is surgically removed from the body, it should be preserved or fixed with a ______ to prevent
the decay of the tissue.

Answer 5

fixative

Question 6

• Small pieces of tissue are placed in solutions of chemicals that cross-link proteins and inactivate degradative enzymes, which preserve cell and tissue structure.

Answer 6

Fixation

Question 7

• To preserve tissue structure and prevent degradation by enzymes released from the cells or
  microorganisms, pieces of organs are placed as soon as possible after removal from the body in solutions
  of stabilizing or cross-linking compounds called fixatives.

Answer 7

FIXATION

Question 8

WHY IS FIXATION IMPORTANT?

Answer 8

1. Avoid tissue destruction by digestive enzymes (autolysis) or through bacterial degradation.
2. Terminate cell metabolism.
3. Hardens the tissue by cross-linking or denaturing proteins.
4. Kill pathogenic microorganisms such as bacteria, fungi, and viruses.

Question 9

Commonly used fixative in fixation

Answer 9

Formalin or formaldehyde
37% - 40%

Question 10

● Only done in specimens such as bone and calcified tissues (and arteries w/ atherosclerosis)

Answer 10

DECALCIFICATION

Question 11

decalcifying agent

Answer 11

Nitric acid

Question 12

Done by successively bathing the specimen in a mixture of ethanol and water from 70% to 100%.

Answer 12

Dehydration

Question 13

In dehydration,_______removes water out of tissue.

Answer 13

Alcohol

Question 14

before infiltration, the fixed tissue must undergo dehydration by having its water
extracted gradually by transfers through a series of increasing ethanol solutions, ending in ________which removes all water.

Answer 14

100% ethanol

Question 15

ASCENDING GRADES OF
ALCOHOL

Answer 15

50%
70%
90%
100%

Question 16

● Removal of the dehydrating agent by immersing the specimen in the solvent that the alcohol and embedding medium is miscible.

Answer 16

CLEARING

Question 17

• Alcohol is removed in organic solvents in which both alcohol and paraffin are miscible.

Answer 17

Clearing

Question 18

T or F|Clearing agent are highly volatile

Answer 18

True - it becomes vapor once exposed to heat

Question 19

Clearing Agents

Answer 19

Xylene and Toluene

Question 20

Between Xylene and Toluene, which is more commonly used?

Answer 20

Xylene

Question 21

After the clearing procedure, the tissue is placed in a melted paraffin
in an oven set at __ -__degree celsius.

Answer 21

52-60 degree Celsius

Question 22

The fully cleared tissue is then placed in melted paraffin in an oven at 52°-60°C, which evaporates the clearing solvent and promotes _______ of the tissue with paraffin

Answer 22

INFILTRATION

Question 23

WHAT IS USED IN iNFILTRATION?

Answer 23

melted paraffin wax

Question 24

is allowing it to harden in a small
container of paraffin at room temperature.

Answer 24

Embedding

Question 25

- makes use of a plastic solution which hardens tissue by cross-linking polymakers. ○ Eliminates the need to use oven and paraffin; little tissue distortion

Answer 25

Plastic resins

Question 26

avoids the higher temperatures needed with paraffin, which helps avoid tissue distortion.

Answer 26

Plastic embedding

Question 27

After the specimen is hardened, it is trimmed into appropriately sized blocks. ○ _____ is removal of excess paraffin.

Answer 27

Cutting

Question 28

In sectioning, the block is mounted in microtome and cut with a _______.

Answer 28

steel knife

Question 29

Sectioning is done with the aid of _____

Answer 29

microtome

Question 30

sections are placed on glass slides and stained for light microscopy or on metal grids for electron-microscopic staining and examination

Answer 30

MOUNTING

Question 31

- Most cells and extracellular material are completely colorless, and to be studied microscopically tissue sections must be (dyed).

Answer 31

STAINING

Question 32

Application of color to the tissue to highlight structures.

Answer 32

Staining

Question 33

Most commonly used stain:

Answer 33

Hematoxylin and Eosin

Question 34

T or F| Hematoxylin and Eosin are insoluble in water

Answer 34

FALSE - These dyes are water soluble

Question 35

blue; basic dye; usually stains nucleus and RNA-containing portion of cytoplasm.

Answer 35

Hematoxylin

Question 36

red; acidic-dye; usually cytoplasmic components and collagen.

Answer 36

Eosin

Question 37

Tissues with negative charges/acids are readily stained with

Answer 37

basic dyes - basophilic

Question 38

Tissues with positive charges are stained with

Answer 38

acidic dyes - acidophilic

Question 39

- stains DNA in the cell nucleus, RNA-rich portions of the cytoplasm, and the matrix of cartilage, producing a dark blue or purple color.

Answer 39

Hematoxylin

Question 40

- stains other cytoplasmic structures and collagen pink.

Answer 40

Eosin

Question 41

considered a counterstain, which is usually a single dye applied separately to distinguish additional features of a tissue.

Answer 41

Eosin

Question 42

Turnaround time for Standard Routine Tissue Processing

Answer 42

5 DAYS

Question 43

- is a faster but more expensive way to do biopsy however it is by case basis.

Answer 43

Frozen Section Biopsy

Question 44

Turnaround time for Frozen Section Biopsy

Answer 44

15 MINUTES

Question 45

○ This method is rapid. ○ Routinely done in hospital to study specimens during surgery.

Answer 45

Frozen Sections

Question 46

In Frozen Sections, ____ and ____ are best preserved in this method

Answer 46

Lipids and Enzymes

Question 47

Fixative agent for frozen section

Answer 47

Liquid Nitrogen