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Botany > GPHT LAB - FIXATION > Flashcards

GPHT LAB - FIXATION Flashcards

1
Q

Makes tissues harder

A

fixation

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2
Q

preserves morphology and chemical constituents of cells and tissues

A

fixation

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3
Q

prevents decomposition and putrefaction of tissues

A

fixation

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4
Q

destroys any microorganisms present in tissue

A

fixation

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5
Q

2 Goals of Fixation

A

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

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6
Q

mechanisms of fixation (2)

A

additive

non-additive

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7
Q

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

A

additive

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8
Q

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

A

non-additive

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9
Q

ex of additive fixatives

A

aldehydes, mercury, osmium tetroxide

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10
Q

ex of non-additive fixatives

A

alcoholic fixatives

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11
Q

tradition temp of fixation

A

RT

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12
Q

Autotech temp of fixation

A

40C

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13
Q

Rapid fixation

A

60C

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14
Q

What must be the volume of fixative for max effectiveness

A

20x that of tissue

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15
Q

ideal tissue:fixative ratio

A

1:20

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16
Q

ideal fixative:tissue ration

A

20:1

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17
Q

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

A

5-10x that of tissue

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18
Q

most common fixative, an aldehyde fixative

A

10% Formalin

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19
Q

ratio used in preparing 10% Formalin

A

1:9

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20
Q

how is 10% Formalin prepared

A

1 part stock solution 37-40% Formalin

9 parts water

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21
Q

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

A

10% Neutral buffered formalin

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22
Q

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

A

neutral pH = less chance of developing formalin artifacts

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23
Q

disadv of formalin (2)

A

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

24
Q

brownish pigments due to action of formic acid with blood

A

formalin pigments

25
Q

brownish pigments w/c can interfere with different processes

A

formalin pigments

26
Q

formalin pigments happens when tissue sample is ___

A

bloody

27
Q

an aldehyde fixative whose action is similar with formalin

A

glutaraldehyde

28
Q

a more pleasing aldehyde fixative because it does not cause irritation

A

glutaraldehyde

29
Q

disadv of glutaraldehyde

A

expensive

30
Q

an aldehyde fixative useful for preserving specimen for electron microscopy

A

glutaraldehyde

31
Q

most common metallic fixative

A

mercuric chloride

32
Q

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

A

mercuric chloride

33
Q

ex of mercuric chloride fixatives [4]

A

Zenker’s
Zenker’s Formol
B5 Fixative
Heidenhain Susa

34
Q

a mercuric chloride fixative for bone marrow

A

B5 Fixative

35
Q

a mercuric chloride fixative for skin tumor biopsy

A

Heidenhain Susa

36
Q

disadv of mercuric chloride

A

tends to form black granular deposits except in Heidenhain Susa

37
Q

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

A

Heidenhain Susa

38
Q

black granular deposits are removed using __

A

iodine

39
Q

metallic fixative for preserving cho

Strong oxidizing agents

A

chromic fixatives

40
Q

metallic fixative for acid mucopolysaccharides

A

lead fixatives

41
Q

used in preserving glycogen and embryos

A

picric acid fixatives

42
Q

disadv of picric acid fixatives

A

1) yellowing of tissues

2) explosive when dry

43
Q

metallic fixative that must be used wet or in solution

A

picric acid fixatives

44
Q

ex of picric acid fixatives

A

Bouin’s

Brasil’s

45
Q

fixative for nucleoproteins

usually added to nuclear fixatives

A

glacial acetic acid

46
Q

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

A

glacial acetic acid

47
Q

2 purposes of alcoholic fixatives

A

fixative

dehydrating agent

48
Q

ex. of alcoholic fixatives

A

ethanol
methanol
isopropyl alcohol

49
Q

most rapid fixative (among all types of fixative)

A

Carnoy’s

50
Q

fixative used at ice-cold temperatures to preserve enzymes

A

acetone

51
Q

fixative used for brain tissues for Rabies diagnosis

A

Acetone

52
Q

fixative and decalcifying agent

A

trichloroacetic acid

53
Q

2 main uses of osmium tetroxide or osmic acid

A

fix and stain fats permanently

fixative for EM

54
Q

disadv of osmium tetroxide or osmic acid

A

expensive
not for routine histopath
corneal blindness

55
Q

why osmium tetroxide or osmic acid not for routine histopath

A

inhibits hematoxylin, a common stain

56
Q

ex of osmium tetroxide or osmic acid

A

Flemming’s Fixative

57
Q

type of fixation for bacteriologic smears

A

heat fixation

Botany (324 decks)

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