Processing and Embedding

Question 1

steps of tissue processing

Answer 1

dehydration, clearing, infiltration

Question 2

dehydration step in tissue processing

Answer 2

series of alcohol in increasing concentrations to remove water to avoid excessive distortion of the tissue

Question 3

most commonly used dehydrating reagent

Answer 3

ethanol

Question 4

dehydrating reagent used to fix blood smears

Answer 4

methanol

Question 5

dehydrating reagent that causes excessive shrinkage

Answer 5

acetone

Question 6

dehydrating reagent that does not harden or shrink tissue as fast as ethanol but cannot be used in staining as it dissolves eosin

Answer 6

isopropyl alcohol

Question 7

displaces ethanol in tissue

Answer 7

clearing

Question 8

intermediate solvent that is miscible with ethanol and paraffin wax

Answer 8

clearing reagent

Question 9

most common clearing reagent

Answer 9

xylene

Question 10

helps remove fat from tissue which may act as a barrier to wax infiltration

Answer 10

clearing

Question 11

process in which tissue is infiltrated with a supporting medium

Answer 11

infiltration

Question 12

infiltrative medium

Answer 12

paraffin wax

Question 13

processing schedule is dependent on these 5 things

Answer 13

-size of specimen
-volume of lab
-type of processor
-time constraints
-reagent choice

Question 14

microwave processing can _______ fixation prior to tissue processing

Answer 14

speed up

Question 15

sources of poor processing (4)

Answer 15

-poor nuclear staining causing cloudy and washed out appearance of tissue
-water in tissue before clearing
-ethanol condensation
-mechanical problem

Question 16

this occurs between fixation and processing to remove calcium salts

Answer 16

decalcification

Question 17

criteria for a good decalcifying agent (4)

Answer 17

-takes the least amount of time
-little or no damage to the cells by acid
-little or no disruption to cell morphology
-does not alter staining properties

Question 18

slow acting decalcifying agent that is gentler in action and less likely to interfere with nuclear staining; can be used alone and good for large tissues

Answer 18

formic acid

Question 19

rapid decalcifying agent that can cause cell shrinkage so you shouldn’t expose tissue to it too long; good for small samples; need to wash formalin before placing in this agent to avoid formation of bischloromethyl ether

Answer 19

hydrochloric acid

Question 20

rapid decalcifying agent but if end-point is exceeded, it will impair staining

Answer 20

nitric

Question 21

slowly binds and removes calcium ions from bone

Answer 21

chelating agents

Question 22

common chelating agent

Answer 22

EDTA

Question 23

gentle to tissue producing minimal artifacts and good staining results

Answer 23

chelating agents

Question 24

chelating agents are not appropriate for this size specimens

Answer 24

large or urgent speciments

Question 25

good when molecular elements need to be preserved for techniques such as IHC, FISH, or PCR (bone marrow biopsies)

Answer 25

chelating agents

Question 26

determining the end point of decal (3)

Answer 26

chemical, radiographic, physical

Question 27

relies upon detection of calcium in the decal solution

Answer 27

chemical method

Question 28

equal parts of ammonium oxalate and ammonium hydroxide and the decal solution

Answer 28

how to use the chemical method to determine when decal is done

Question 29

decalcification is complete if test aliquot is

Answer 29

colorless or clear

Question 30

decalcification is incomplete if the test aliquot is

Answer 30

cloudy or turbid

Question 31

why does undecalcified/overdecalcification occur (3)

Answer 31

-TAT -poor end point determination -wrong decal

Question 32

the longer a bone marrow biopsy is in decal, it can start to remove this

Answer 32

iron

Question 33

bone marrow biopsies should be in decal no longer than _______

Answer 33

45 min to an hour

Question 34

the end point of a bone marrow biopsy decalcification is

Answer 34

hard to determine

Question 35

blocking of tissue section which involves enclosing the tissue in infiltration medium

Answer 35

embedding

Question 36

multiple tissue pieces are aligned this way

Answer 36

across the long axis of the mold

Question 37

tissues with an epithelial surface are embedded to provide sections in a plane _______ to the surface

Answer 37

right angle/perpendicular