CONVENTIONAL TISSUE PROCESSING AND RAPID TISSUE PROCESSING

Question 1

Enumerate the steps in tissue processing

Answer 1

1. Fixation
2. Decalcification
3. Dehydration
4. Clearing
5. Infiltration (Impregnation)
6. Embedding
7. Sectioning (Microtomy)
8. Mounting
9. Staining
10. Labeling

Question 2

critical step in the preparation of histological sections

Answer 2

Fixation

Question 3

optional step in tissue processing

Answer 3

Decalcification

Question 4

True or False
- melted paraffin wax is hydrophilic

Answer 4

False
-melted paraffin wax is hydrophobic (not miscible with water), most of the water in a specimen must be removed before it can be infiltrated with wax

Question 5

commonly carried out by immersing specimens in a series of ethanol (alcohol) solutions with increasing concentration to avoid excessive distortion of tissue until a water-free tissue in alcohol is reached

Answer 5

Dehydration

Question 6

dehydrated tissue is transferred to an intermediate solvent that is fully miscible with both ethanol and paraffin wax

Answer 6

Clearing

Question 7

clearing agents impart an _____________ or ______________ to the tissue due to their relatively high refractive index

Answer 7

optical clarity or transparency

Question 8

True or False
- Clearing remove a substantial amount of fat from the tissue which otherwise presents a barrier to wax infiltration

Answer 8

True

Question 9

tissue is oriented and placed in a mold that is filled with molten wax to form a solid tissue block that can later be clamped into a microtome for sectioning

Answer 9

Embedding

Question 10

most important step in embedding

Answer 10

correct orientation of tissue
- incorrect placement of tissues may result in diagnostically important tissue elements being missed or damaged during microtomy

Question 11

one of the most directly correlated factors in tissue sectioning

Answer 11

thickness

Question 12

warm bath should be kept at _____C below the melting point of the embedding wax

Answer 12

5-10°C

Question 13

True or False
- xylene removes the absolute alcohol and absolute alcohol removes the paraffin

Answer 13

False
- xylene removes the paraffin and absolute alcohol removes the xylene

Question 14

True or False
- high temperature cause tissue to shrink and to become hard and brittle
- low temperature increases the viscosity of reagents used in tissue processing, thereby reducing the rate of diffusion and increasing processing time

Answer 14

True

Question 15

tissue shrinkage during infiltration in paraffin wax results mainly the effect of heat on __________

Answer 15

collagen

Question 16

True or False
- high pressure increases the infiltration rate and decrease the time needed to complete steps

• reduce pressure facilitates infiltration of dense specimens with the more viscous embedding media

Answer 16

False
- reduced pressure increases the infiltration rate and decrease the time needed to complete steps

• high pressure facilitates infiltration of dense specimens with the more viscous embedding media

Question 17

True or False
- vacuum reduce the infiltration time when dealing with dense and fatty tissue specimens

Answer 17

True

Question 18

True or False
- In general, needle biopsies and bloody specimens should be incubated conservatively, whereas fatty specimens can be processed for longer than average.

Answer 18

True

Question 19

microwave assisted processing allows dehydration to be done in only ___ step and employs a _____-step process involving a single change each in ethyl alcohol and isopropanol followed by two changes in paraffin

Answer 19

one step and employs a four-step process

Question 20

In microwave heating technique, what is being elimanted?

Answer 20

Xylene
- When exposed to these high microwave temperatures, the alcohols quickly heat and dissipate, while the paraffin remains inert, allowing the paraffin to fully infiltrate the specimen. This eliminates the use of xylene from the process

Question 21

In microwave processing, 60% to 80% faster than conventional processing time with an hourly throughput of up to ___ specimens

Answer 21

120 specimens

Question 22

Microwave processing is commonly employed to unmask or retrieve antigens with the use of ___________________________

Answer 22

10 mm citrate buffer (pH 6.0)

Question 23

Metallic stains temperature?

Answer 23

75° to 95°C

Question 24

Non-metallic stains temperature?

Answer 24

55° to 60°C

Question 25

one critical aspect of using microwave techniques is ensuring that samples have been adequately ______

Answer 25

fixed

Question 26

In the last step of RTP using microwave, tissue must be brought to the boiling point of the intermedium (82°C for ____________ and 78°C for _____________) to "flash evaporate" the remaining ethyl alcohol or propanol

Answer 26

82°C for ethyl alcohol and 78°C for isopropanol