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02 Fixation Flashcards

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1
Q

first step in histotechnology

A

fixation

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2
Q

chemical process by which biological tissues are preserved from decay

A

fixation

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3
Q

process of preserving cells and tissue constituents in a life-like manner

A

fixation

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4
Q

basic mechanism in fixation

(additive / non-additive)

cross linking fixatives

A

additive

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5
Q

basic mechanism in fixation

(additive / non-additive)

chemical constituent taken into the cell, forming molecular complexes and stabilizing proteins

A

additive

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6
Q

basic mechanism in fixation

(additive / non-additive)

formalin, mercury, osmium tetroxide

A

additive

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7
Q

basic mechanism in fixation

(additive / non-additive)

fixing agent is not incorporated into the tissue

A

non-additive

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8
Q

basic mechanism in fixation

(additive / non-additive)

alteration of tissue composition by removing bound water molecule at hydrogen bonds within protein molecules

A

non-additive

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9
Q

basic mechanism in fixation

(additive / non-additive)

stabilizes proteins by forming crosslinks after water molecule removal

A

non-additive

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10
Q

satisfactory fixation occurs at what pH level?

A

6-8

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11
Q

high acidity ___ (increases/decreases) effectiveness

A

decreases

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12
Q

what is the relationship of temperature to the diffusion into the tissue?

A

direct (increased temp = increased diffusion)

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13
Q

what is the relationship of diffusion into the tissue and rate of chemical reaction between the fixative and tissue elements?

A

direct

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14
Q

temperature of fixation of surgical specimens

A

room temp

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15
Q

the fixation of surgical specimens can be followed by further fixation at what temperature after fixating it at room temperature?

A

40-45C

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16
Q

temperature of fixation:

electron microscopy

A

0-4C

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17
Q

temperature of fixation:

mast cells for EM

A

room temp

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18
Q

T/F: nucleic acids easily react with fixatives at room temp

A

F (do not react)

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19
Q

chemical reactions are rapid at ___ (low/high) temp

what temp?

A

high
60-65C

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20
Q

the thickness of the section to be fixed should be ___

A

1-2mm for EM
2cm for light microscopy

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21
Q

the brain is usually suspended whole in ___ buffered formalin for ___ weeks to ensure fixation and some hardening prior to secitoning

A

10%
2-3

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22
Q

hypertonic solutions give rise to ___ ___

A

cell shrinkage

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23
Q

isotonic and hypotonic fixatives cause ___ and ___ ___

A

swelling
poor fixation

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24
Q

the best results is usually obtained using slightly ___ (osmolality) solutions

what mOsm?

A

hypertonic
400-450

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25
give the concentration of fixatives: formaldehyde
10%
26
give the concentration of fixatives: glutaraldehyde
3%
27
presence of buffer causes polymerization of ___, with consequent ___ (increase/decrease) in its effective concentration
aldehyde decrease
28
give the concentration of fixatives: glutaraldehyde for immunoelectrochemistry
0.25%
29
primary fixation in buffered formalin is usually carried out for ___ hours during the day the specimen is obtained
2-6
30
___ fixation may cause shrinkage and hardening of the tissue and may severely inhibit enzyme activity and immunological reaction
prolonged fixation
31
the specimen should be placed in a fixative solution as soon as it is removed from the body to prevent ___ and ___
autolysis and putrefaction
32
the volume of fixative should be ___ times the volume of the tissue to be fixed
10-25
33
the maximum effectiveness of fixation is noted to be ___ times the tissue volume
20
34
fibrous organ take ___ (longer/shorter) than small or loosely textured tissues such as biopsies or scrapings
longer
35
fixation time can be cut down using ___, ___, ___, or ___
heat vacuum agitation microwave
36
to maintain an adequate fixation time of 4-6 hours, the tissue size must be ___ square
2cm
37
T/F: refrigeration is used to slow down decomposition if the tissue that needs to be photographed and cannot be fixed immediately
T
38
classification of fixative: made up only of one substance
simple fixative
39
classification of fixative: two or more fixatives to obtain optimal combined effect
compound
40
aldehyde fixatives used (2)
formaldehyde glutaraldehyde rmmbr: these are simple fixatives!
41
metallic fixatives used (3)
mercuric chloride chromate fixatives lead fixatives (M-C-L) rmmbr: these are simple fixatives!
42
classification of fixative: preserve specific parts and particular microscopic elements
cytologic fixatives
43
simple fixatives used (6)
picric acid acetic acid acetone alcohol osmium tetroxide heat (P-A-A-A-O-H)
44
microanatomical fixatives used for general microscopic study of tissue structures (8)
10% formol saline 10% neutral buffered formalin Heidenhain's Susa Formol Sublimate (formol corrosive) Zenker's solution Zenker-formol (Helly's solution) Bouin's solution Brasil's solution
45
composition of Helly's solution
Zenker-formol
46
nuclear fixatives that use glacial acetic acid as primary component (5)
Carnoy's fluid Heidanhain's susa Bouin's fluid Newcomer's fluid Flemming's fluid (C-He-Bo-Ne-Fl)
47
cytoplasmic fixatives (5)
Flemming's fluid without acetic acid Helly's fluid Formalin with Post-chroming Regaud's Fluid (moller's fluid) Orth's fluid
48
histochemical fixatives that preserve chemical constituents of cells and tissues (4)
10% formol saline Absolute ethyl alcohol Acetone Newcomer's fluid
49
type of fixation used for lipid fixation
aldehyde fixatives
50
type of fixation for carbohydrates that allow better retention
alcoholic fixatives
51
arrange the following in order of DECREASING speed of penetration: acetic acid osmium tetroxide picric acid formaldehyde ethyl/methyl alcohol mercuric chloride
formaldehyde > acetic acid > mercuric chloride > ethyl/methyl alcohol / osmium tetroxide > picric acid (F-A-M-E-O-P)
52
this type of fixative form cross-links between proteins, creating a gel, thus retaining cellular constituents in their in vivo relationships to each other
aldehyde fixatives
53
this fixative is produced from oxidation of methyl alcohol
formaldehyde
54
fixation time of formaldehyde
24 hrs
55
fixative for routine paraffin sections, EM, histochemistry, & enzyme studies
10% formalin
56
diluent of 10% formol-saline
10% NaCl solution
57
used as a fixative of CNS tissues
10% formol-saline
58
fixation time of formol-saline and its optimal temperature (2)
24 hrs at 35C 48 hrs at RT
59
fixative used for the preservation and storage of surgical, post-mortem, and research specimen
10% neutral buffered formalin
60
fixation time of 10% neutral buffered formalin
2-4 hrs
61
fixative recommended for routine post-mortem tissues
formol-corrosive
62
components of 10% neutral buffered formalin
3.5 g sodium dihydrogen phosphate 6.5 g disodium hydrogen phosphate 100 mL 40% formaldehyde 900 mL distilled water
63
components of 10% formol-saline
100 mL 40% formaldehyde 9 g NaCl 900 mL distilled water
64
components of formol-corrosive
90 mL saturated aqueous mercuric chloride 10 mL formaldehyde
65
fixative time of formol-corrosive
3-24 hrs
66
this fixative brightens cytoplasmic and metachromatic stains
formol-corrosive
67
this fixative bind with sulfhydryl groups in acidic solutions
metallic fixatives
68
an excellent trichome stain and is included in most compound fixatives
5-7% mercuric chloride
69
in 5-7% mercuric chloride, pigments are removed by treatment with iodide solution in ___
95% alcohol
70
components of 5-7% mercuric chloride
5 g mercuric chloride 2.5 g potassium dichromate 1 g sodium sulfate 100 mL distilled water
71
fixative for liver, spleen, connective tissue fibers, and nuclei
Zenker's fluid
72
fixation time of Zenker's fluid
12-24 hrs
73
this fixative permits brilliant staining of nuclear and connective tissue fibers
Zenker's fluid
74
this fixative lyses RBC and can make tissues brittle
Zenker's fluid
75
components of Zenker's fluid
95 mL stock solution 5 mL glacial acetic acid 5mL
76
fixative used for pituitary gland, bone marrow, and blood containing organs like spleen and liver
Zenker-formol
77
fixative recommended for tumor biopsies of the skin
Heidenhain's susa solution
78
fixation time of Heidenhain's susa solution
3-12 hrs
79
fixative commonly used for bone marrow biopsies
B-5 fixative
80
fixation time of B-5 fixative
1-2 hrs
81
this fixative preserves carbohydrates and precipitates all proteins; but may produce sub-oxide precipitates
1-2% chromic acid
82
this fixative preserves lipids and mitochondria
3% potassium dichromate
83
fixation time of Regaud's fluid
12-48 hrs
84
fixative recommended for demonstration of chromaffin tissues, mitochondria, mitotic figures, golgi bodies, RBC, and colloid-containing tissues
Regaud's fluid
85
components for Regaud's fluid
80 mL 3% potassium dichromate 20 mL 40% formaledhyde
86
fixation time of Orth's fluid
36-72 hrs
87
this fixative is recommended for study of early degenerative processes and tissue necrosis
Orth's fluid
88
fixative recommended for acid mucopolysaccharides and fixes connective tissue mucin
4% lead acetate
89
T/F: the mechanism of picric acid as a fixative is still unknown
T
90
T/F: picric acid is insoluble in water
F
91
the yellow color caused by picric acid can be removed by ___ ___ or washing with ___
lithium carbonate 50-70% ethanol
92
fixative that penetrates and fixes small tissue rapidly
1% picric acid solution
93
fixative that is excellent for glycogen demonstration and suitable for aniline stains
1% picric acid solution
94
1% picric acid solution is not suitable for ___ as it causes crumbling when the sections are cut
frozen sections
95
preferred fixative for connective tissue staining
Bouin's solution
95
fixative that is excellent for soft and delicate tissues with minimal distortion of microanatomical structures
Bouin's solution
96
a picric acid fixative that is less messy than Bouin's solution
Brasil's alcoholic picroformol fixative
97
a fixative that is normally used in conjunction with other fixatives to form a compound solution
glacial acetic acid
98
T/F: alcohol is used both for fixation and dehydration
T
99
the most rapid fixative
Carnoy's fluid
100
an alcohol fixative that produces better reaction in Feulgen stain
Newcomer's fluid
101
fixative recommended for fixing mucopolysaccharides
Newcomer's fluid
102
this fixative conjugate fats and lipids permanently by making them insoluble to alcohol and xylene during dehydration and clearing
6% osmium tetroxide
103
this fixative has a softening effect on dense fibrous tissues and precipitates proteins
trichloroacetic acid
104
a fixative used at ice cold temperature (-5 to 4C) that is recommended for the study of water diffusible enzymes such as phosphatases and lipases
acetone
105
used in fixing brain tissues for diagnosis of rabies
acetone carnoy's
106
employed fixation technique for frozen tissue sections and bacteriologic smears
heat

MT6321 (9 decks)

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