GPHT LAB - FIXATION

Question 1

Makes tissues harder

Answer 1

fixation

Question 2

preserves morphology and chemical constituents of cells and tissues

Answer 2

fixation

Question 3

prevents decomposition and putrefaction of tissues

Answer 3

fixation

Question 4

destroys any microorganisms present in tissue

Answer 4

fixation

Question 5

2 Goals of Fixation

Answer 5

preserves morphology and chemical constituents of cells and tissues
harden the tissues for further processing

Question 6

mechanisms of fixation (2)

Answer 6

additive

non-additive

Question 7

mechanisms of fixation
fixative becomes part of tissue by forming crosslinks or bridges
these bridges stabilize proteins, thus fixing the tissue

Answer 7

additive

Question 8

mechanisms of fixation
fixative does not become part of the tissue
works by removing water present

Answer 8

non-additive

Question 9

ex of additive fixatives

Answer 9

aldehydes, mercury, osmium tetroxide

Question 10

ex of non-additive fixatives

Answer 10

alcoholic fixatives

Question 11

tradition temp of fixation

Answer 11

RT

Question 12

Autotech temp of fixation

Answer 12

40C

Question 13

Rapid fixation

Answer 13

60C

Question 14

What must be the volume of fixative for max effectiveness

Answer 14

20x that of tissue

Question 15

ideal tissue:fixative ratio

Answer 15

1:20

Question 16

ideal fixative:tissue ration

Answer 16

20:1

Question 17

if expensive fixatives are used like osmium tetroxide, what must be the volume

Answer 17

5-10x that of tissue

Question 18

most common fixative, an aldehyde fixative

Answer 18

10% Formalin

Question 19

ratio used in preparing 10% Formalin

Answer 19

1:9

Question 20

how is 10% Formalin prepared

Answer 20

1 part stock solution 37-40% Formalin

9 parts water

Question 21

an aldehyde fixative, addition of phosphate buffer adjusted to pH 7

Answer 21

10% Neutral buffered formalin

Question 22

why is 10% Neutral buffered formalin better than 10% formalin

Answer 22

neutral pH = less chance of developing formalin artifacts

Question 23

disadv of formalin (2)

Answer 23

irritating to nose (rhinitis), eyes (excessive lacrimation), skin (allergic dermatitis)
formalin pigment production

Question 24

brownish pigments due to action of formic acid with blood

Answer 24

formalin pigments

Question 25

brownish pigments w/c can interfere with different processes

Answer 25

formalin pigments

Question 26

formalin pigments happens when tissue sample is ___

Answer 26

bloody

Question 27

an aldehyde fixative whose action is similar with formalin

Answer 27

glutaraldehyde

Question 28

a more pleasing aldehyde fixative because it does not cause irritation

Answer 28

glutaraldehyde

Question 29

disadv of glutaraldehyde

Answer 29

expensive

Question 30

an aldehyde fixative useful for preserving specimen for electron microscopy

Answer 30

glutaraldehyde

Question 31

most common metallic fixative

Answer 31

mercuric chloride

Question 32

metallic fixative very useful to visualize cell detail used in tissue photography

Answer 32

mercuric chloride

Question 33

ex of mercuric chloride fixatives [4]

Answer 33

Zenker's Zenker's Formol B5 Fixative Heidenhain Susa

Question 34

a mercuric chloride fixative for bone marrow

Answer 34

B5 Fixative

Question 35

a mercuric chloride fixative for skin tumor biopsy

Answer 35

Heidenhain Susa

Question 36

disadv of mercuric chloride

Answer 36

tends to form black granular deposits except in Heidenhain Susa

Question 37

all mercuric chloride fixatives tends to form black granular deposits except in ______

Answer 37

Heidenhain Susa

Question 38

black granular deposits are removed using __

Answer 38

iodine

Question 39

metallic fixative for preserving cho | Strong oxidizing agents

Answer 39

chromic fixatives

Question 40

metallic fixative for acid mucopolysaccharides

Answer 40

lead fixatives

Question 41

used in preserving glycogen and embryos

Answer 41

picric acid fixatives

Question 42

disadv of picric acid fixatives

Answer 42

1) yellowing of tissues | 2) explosive when dry

Question 43

metallic fixative that must be used wet or in solution

Answer 43

picric acid fixatives

Question 44

ex of picric acid fixatives

Answer 44

Bouin's | Brasil's

Question 45

fixative for nucleoproteins | usually added to nuclear fixatives

Answer 45

glacial acetic acid

Question 46

fixative not suitable for cytoplasmic fixation because cells will swell and burst

Answer 46

glacial acetic acid

Question 47

2 purposes of alcoholic fixatives

Answer 47

fixative | dehydrating agent

Question 48

ex. of alcoholic fixatives

Answer 48

ethanol methanol isopropyl alcohol

Question 49

most rapid fixative (among all types of fixative)

Answer 49

Carnoy's

Question 50

fixative used at ice-cold temperatures to preserve enzymes

Answer 50

acetone

Question 51

fixative used for brain tissues for Rabies diagnosis

Answer 51

Acetone

Question 52

fixative and decalcifying agent

Answer 52

trichloroacetic acid

Question 53

2 main uses of osmium tetroxide or osmic acid

Answer 53

fix and stain fats permanently | fixative for EM

Question 54

disadv of osmium tetroxide or osmic acid

Answer 54

expensive not for routine histopath corneal blindness

Question 55

why osmium tetroxide or osmic acid not for routine histopath

Answer 55

inhibits hematoxylin, a common stain

Question 56

ex of osmium tetroxide or osmic acid

Answer 56

Flemming's Fixative

Question 57

type of fixation for bacteriologic smears

Answer 57

heat fixation