Fixation

Front 1

Substitution of alcohol as the diluting solution for formaldehyde results in better preservation of..

Back 1

glycogen

Front 2

Polymerized formaldehyde is known as

Back 2

paraformaldehyde

Front 3

recommended minimum time for fixation in formalin

Back 3

6-8 hours

Front 4

a good fixative of CNS tissue to be stained with silver or gold techniques is

Back 4

formalin ammonium bromide

Front 5

T/F

formalin penetrated rapidly but fixes slowly

Back 5

true

Front 6

PEL for formaldehyde

Back 6

.75 ppm

Front 7

formaldehyde cross-links proteins by reacting with

Back 7

NH2

Front 8

formalin pigment will be formed when the pH is

Back 8

acidic

Front 9

How many milliliters of a 5% solution will 2.5 g make?

Back 9

50

Front 10

T/F

formalin fixation stabilizes lipids

Back 10

false

Front 11

formaldehyde reacts with protein side-chains by combining with the ______ group

Back 11

amino group

Front 12

the primary purpose of fixation

Back 12

stop enzymatic action

Front 13

methylane bridges are formed during the reaction of certain tissue groups with

Back 13

formaldehyde

Front 14

commercial stock formaldehyde solutions contain __% formaldehyde

Back 14

37-40%

Front 15

the volume of fixative should exceed the volume of the tissue by

Back 15

15 - 20 times

Front 16

absolute alcohol is indicated as a primary fixative if the tissue is to be processed for the determination of

Back 16

urate crystals

Front 17

generally, an increase in temperature of the fixative solution also increases

Back 17

the speed of fixation

Front 18

1 cm is equivalent to ______ micrometers

Back 18

10,000

Front 19

1 km is equal to about ____ pounds

Back 19

2.2

Front 20

T/F formalin ammonium bromide is a good fixative for connective tissue

Back 20

false

Front 21

substitution of alcohol as the diluting solution for formaldehyde results in

Back 21

better preservation of glycogen

Front 22

To prepare a 10% solution of formalin, which of the following amounts of water should be added to 100mL of stock formaldehyde?

Back 22

900 mL

Front 23

10% formalin is the same as ___% formaldehyde

Back 23

4%

Front 24

the first and most important procedure in the preparation of a tissue for microscopic examination is the choice of

Back 24

fixative

Front 25

For the best results when using formalin as a routine fixative, it must be made

Back 25

neutral

Front 26

Tissue fixed in glutaraldehyde is not satisfactory for which reaction

Back 26

PAS (periodic acid-Schiff's) reaction

Front 27

purification is caused by

Back 27

bacterial action

Front 28

1 cubic cm = ____ liters

Back 28

.001 liter

Front 29

Depending on the reagent used, what may cause tissue to become overhardened?

Back 29

prolonged fixation

Front 30

Buffered solutions are important because these solutions:

Back 30

resist pH changes when either a weak acid or a weak base is added

Front 31

What temperature in Celsius corresponds to 20 degrees F?

Back 31

-6.6

Front 32

ethyl alcohol is a _____ fixative

Back 32

nonadditive

Front 33

T/F Since formalin is a coagulant fixative it is considered an excellent fixative for paraffin embedding

Back 33

False

Front 34

T/F Formalin pigment can be removed from tissue by immersion in alcoholic picric acid

Back 34

True

Front 35

T/F Glutaraldehyde is frequently used to fix specimens for electron microscopy

Back 35

True

Front 36

T/F Fat is well preserved by Carnoy solution

Back 36

False

Front 37

Formalin pigment can be removed from tissue by using..

Back 37

alcoholic picric acid

Front 38

T/F Mercury pigment can be removed from the tissue by immersion in sodium thiosulfate

Back 38

False

mercury pigment is removed by iodine, the iodine is then removed by sodium thiosulfate

Front 39

T/F Chrome pigment can be prevented by washing tissues with water following fixation

Back 39

True

Front 40

H&E stained sections of liver fixed in the microwave oven show marked pyknotic, overstained nuclei. This can probably be prevented in the future by ensuring that the temperature is kept below

Back 40

55 degrees celsius

Front 41

Which fixative must be used under a hood because it readily vaporizes and will fix the nasal mucosa?

Back 41

osmium tetroxide

Front 42

T/F The best fixing fluid for the preservation of nuclear detail is buffered formalin.

Back 42

False - Acetic acid and Carnoy solution are preferred for nuclear fixation

Front 43

Fixatives containing ______ usually require washing in water.

Back 43

chromate salts

Front 44

Precipitate left in tissues that have been fixed in solutions containing mercuric chloride may be removed by immersion in

Back 44

iodine

(Gram or Lugol iodine)

Front 45

T/F Glyoxal fixatives are rapid-acting compared to formaldehyde

Back 45

True

Front 46

T/F Acetone is used when a rapid-acting fixative is needed

Back 46

True

Front 47

___ is a satisfactory replacement for mercury in some fixative solutions.

Back 47

Zinc

Front 48

T/F Acetic acid is an excellent nuclear fixative.

Back 48

True

Front 49

_____ is not a satisfactory fixative if silver stains for Helicobacter pylori are needed (as on gastric biopsies), as staining is unsatisfactory.

Back 49

Glyoxcal