Tissue Selection and Fixation

Question 1

most important step in histology

Answer 1

fixation

Question 2

this process stabilizes the protein in the tissue

Answer 2

fixation

Question 3

if tissue is not fixed, this bacterial attack can occur

Answer 3

putrefaction

Question 4

size of specimens

Answer 4

no thicker than a nickel, no larger than a post stamp

Question 5

volume of fixative should be at least_________ than tissue volume

Answer 5

15-20x greater

Question 6

fx of fixation (5)

Answer 6

-maintain relationship between cell and extracellular substances
-helps with refractive index, increasing contrast between tissue elements
-helps in grossing since tissue will be firm
-enhances to stain (takes up stain better)
-stabilize tissue elements

Question 7

physical method of stabilizing proteins by fixation

Answer 7

heat and desiccation

Question 8

stabilizes and denatures protein (oven/microwave)

Answer 8

heat

Question 9

air drying is used for touch prep for what stain

Answer 9

Giemsa

Question 10

primary method of fixation with the use of one or more reagents

Answer 10

chemical methods

Question 11

what affects the quality of fixation (5)

Answer 11

-size of specimen
-volume of fixative
-time spent in the fixative
-temperature
-choice of fixative

Question 12

interval between interruption of blood supply and placement in fixative

Answer 12

ischemic time

Question 13

max amount of time specimens are in formalin

Answer 13

72 hours

Question 14

breast tissue should be in contact with formalin for ________ hours and not exceed 72 hours

Answer 14

6-48 hours

Question 15

three time points that should be recorded

Answer 15

-time tissue is removed
-time tissue is received in the gross room
-time tissue is placed into formalin

Question 16

to prevent the loss of ER/HER2 activity, breast fixation should begin

Answer 16

less than one hour

Question 17

minimum of ________ hours in formalin is required for reliable ER/PR assay results

Answer 17

6-8

Question 18

most fixation takes place at this temperature

Answer 18

room temperature

Question 19

microwave fixation temperature

Answer 19

45 deg celcius

Question 20

since urate crystals are water soluble, they need this type of fixative

Answer 20

non aqueous, alcohol

Question 21

10% neutral buffered formalin, how much formalin is actually in it

Answer 21

3.7%

Question 22

what can happen if unbuffered formalin ages

Answer 22

formic acid can develop and lower the pH

Question 23

this causes crystals of formalin pigment (hematin) to be deposit throughout tissue

Answer 23

low pH

Question 24

these can be removed by immersing the sections in saturated alcohol with picric acid for 10 min -3 hours, then washed with water

Answer 24

formalin pigment

Question 25

picric acid saturated aqueous solution, made of 40% formaldehyde and glacial acetic acid, fixed for 4-18 hours

Answer 25

Bouin's solution

Question 26

40% formaldehyde, 95% alcohol and 0.5g of calcium acetate to make neutral, fixed for 12-24 hours

Answer 26

alcoholic formalin

Question 27

bouin's is usually used to fix tissue that is stained with this

Answer 27

Trichome

Question 28

tissue will be this color due to the picric acid in Bouins

Answer 28

yellow

Question 29

Bouins preserves this well but lyses erythrocytes

Answer 29

glycogen

Question 30

this fixative is used during processing to complete fixation following an incomplete primary formalin fixation

Answer 30

alcoholic formalin

Question 31

this fixative can be used for fixation or post-fixation of large fatty specimens (breast) because lymph nodes can be more easily detected bc of lipid extraction

Answer 31

alcoholic formalin

Question 32

absolute ethanol, glacial acetic acid, chloroform and fixes for 1-4 hours

Answer 32

Carnoy's solution

Question 33

this fixative is usually used for lymph node dissections

Answer 33

Carnoy' solution

Question 34

gives good nuclear presentation, fast acting while lysing erythrocytes and dissolving lipids but can also produce excessive hardening and shrinkage

Answer 34

Carnoy's solution

Question 35

this fixative made with 0.5% zinc chloride is used with hematopoietic, lymphoid tissue and other tissues if a lymphoproliferative disorder is suspected, fixes for 2 hours

Answer 35

B-plus fixative

Question 36

produces excellent nuclear detail with good results with many special stains, recommended for IHC, and mostly used for bone marrow cores

Answer 36

B-plus fixative

Question 37

transport medium used for specimens that need immunoflorescence procedure; kidney biopsies

Answer 37

Michel's transport medium

Question 38

this fixative is not recommended for muscle biopsies

Answer 38

Michel's medium

Question 39

electron microscopy fixatives (3)

Answer 39

glutaraldehyde, osmium tetroxide, formaldehyde

Question 40

EM fixative need to be fixed for _______hours or else the tissue will harden

Answer 40

less than 2 hours

Question 41

delayed fixation can lead to

Answer 41

autolysis

Question 42

if there is delayed fixation, what can you do (3)

Answer 42

-fix in 15-20x volume of tissue asap -open and pin specimens -bread loaf

Question 43

tissue sections can blow in the water bath after sectioning, smudgy nuclei with no chromatin pattern with nuclear bubbling if this occurs

Answer 43

incomplete fixation