FIXATION Flashcards
(104 cards)
1
Q
most critical step in routine histopathology
A
fixation
2
Q
goals of fixation
A
- preserve morphological and chemical integrity of the cell
2. harden and preserve tissue
3
Q
action of fixatives
A
- preserves the tissue by stopping all cellular activities
2. prevent autolysis by inactivating lysosomal enzymes
4
Q
fixation pH
A
6-8
5
Q
fixation osmolality
A
slightly hypertonic
6
Q
fixation rate of penetration
A
1 mm/hour
7
Q
rapid fixation temp
A
60 C
8
Q
routine histopath fixation temp
A
22-25 C
9
Q
electron microscopy and histochem fixation temp
A
0-4 C
10
Q
autotechnicon fixation temp
A
40 C
11
Q
tb patients fixation temp
A
100 C
12
Q
mercury refrigerator fixation temp
A
4 C
13
Q
buffered formalin duration
A
2-6 hours
14
Q
electron microscopy duration
A
3 hours
15
Q
hastens fixation
A
small and loose tissues, agitation, heat, microwave, vacuum
16
Q
retards fixation
A
fibrous tissues, blood, mucus, fats, and cold temp
17
Q
routine histopath fixation volume
A
10-20x of the tissue
usually, 20:1
18
Q
expensive fixation volume
A
5-10x of the tissue
19
Q
museum fixation volume
A
50x of the tissue
20
Q
brain special consideration (spc)
A
- tied at the circle of willis
2. fixed for 2-3 weeks in 10% neutral buffered formalin
21
Q
large solid tissues (uterus) spc
A
cut open and sliced thinly
22
Q
hollow organs spc
A
place cotton inside or open organs entirely
23
Q
air filled lungs spc
A
covered with gauze
24
Q
eyes spc
A
fixative is injected
25
hard tissues (nails) spc
immersed in tissue softeners
26
fixative that forms cross-links with the tissue
additive fixatives
27
fixative that removes water in the tissue
alcoholic/dehydrating agents
28
cytological fixative that preserves nucleus and chromatin. also contains glacial acetic acid
nuclear fixative
29
cytological fixative that preserves membrane bound organelles. should not contain glacial acetic acid.
cytoplasmic fixative
30
cytological fixative that preserves biochemical components (fats, enzymes).
histochemical
31
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microanatomical fixative (7)
1010 hfb zb
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10% formol saline
10% BNF
heidenhain's susa
formol sublimate
bouin's
zenker's
brasil's
```
32
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nuclear fixative (5)
fch nb
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flemming's
carnoy's
heidenhain's susa
newcomer's
bouin's
```
33
cytoplasmic (5)
| fk fro
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flemming's w/o hoac
helly's
formalin
regaud's (moller's)
orth's
```
34
histochemical (4)
| 10 aan
10% formol saline
absolute ethanol
acetone
newcomer's
35
fixation of CNS tissue, post-mortem tissues, and silver impregnation techniques
10% formol saline
36
routine histopath fixative, also for tissues with iron pigments and elastic fibers
10% BNF
37
fixative for silver reticulin methods and post-mortem tissues
formol sublimate
38
fixative for glycogen and sputum
alcohol formalin (gendre's fixative)
39
fixative for enzyme histochem and electron microscopy, has 2 concs
glutaraldehyde
2.5% - small tissue fragments and needle biopsy
4% - larger tissue specimens
40
aldehyde fixative for ultrathin sections
paraformaldehyde
41
most common metallic fixative
mercuric chloride
42
process where we remedy black granule ppts from metallic fixatives
dezenkerization
43
dezenkerization solution
96% alcohol and 5% sodium thiosulfate
44
fixative of choice for cell detail preservation and tissue photography; permits brilliant metachromatic staining of cells
mercuric chloride
45
fixative for small pieces of liver, spleen, and nuclei
zenker's
46
fixative for pituitary gland, bone marrow, and blood containing organs
helly's / zenker's formol
47
fixative for skin tumor biopsy
heidenhain's susa
susa:
Sublimat - mercuric chloride
Saure - acid
48
fixative for bone marrow biopsies
B5 fixative
49
this fixative is carcinogenic and used for carbohydrate preservation
chromate fixatives
50
fixative for lipid and mitochondria demonstration
potassium dichromate
51
fixative for golgi bodies and colloid containing tissues
regaud's
52
fixative for rickettsia demonstration, tissue necrosis, and myelin preservation
orth's
53
forms lead carbonate precipitate and for acid mucopolysaccharides and mucins preservation
lead fixatives
54
fixative that is explosive in dry forms, can also be used as a decalcifying agent
picric acid fixatives
55
major disadvantage of picric acid fixative
yellow stain
56
remedy for the major disadvantage of picric acid fixative
wash the tissue with 50-70% alcohol
57
excellent fixative for glycogen and small tissue fragments
picric acid fixative
58
true or false. since picric acid imparts a stain, this may also be used as a stain.
true
59
fixative for embryo and pituitary biopsies
bouin's
60
fixative for glycogen
picroformol fixative
61
fixative for GIT samples and endocrine tissues, has decalcifying properties too
hollande's
62
preferred fixative among all picric acid fixatives
picroformol fixative
63
fixative that rapidly denatures and ppts protein
alcoholic fixatives
64
fixative for dry and wet blood/blood marrow smears
| disadv: can cause blindness
methanol
65
fixative for touch preparation
isopropanol
66
fixative for PCR, used for cytological smears (Pap smear, 95% ethanol), cant fix glycogen
ethanol
67
most rapid fixative (1-3 hrs)
carnoy's
68
fixative for chromosome, lymph nodes, brain tissue for rabies dx, and urgent biopsies
carnoy's
69
fixative for nuclear, histochemical, and biochemical
newcomers
70
fixative of choice for ultrathin sectioning
osmium tetroxide
71
most common chrome-osmium acetic acid fixative,
| excellent fixative for nuclear structures
flemming's
72
fixative that precipitates nucleoproteins and chromatin material
glacial acetic acid fixatives
73
fixative for rabies dx and preservation of water-diffusible enzymes (lipases and phosphatases)
acetone fixatives
74
fixation method for bacteriologic smears
heat fixation
75
rapid physical method of fixation, demonstration of neurochemical substances in the brain (acetylcholine)
microwave fixation
76
tissue is fixed on another fixative
secondary fixation
77
secondary fixation using 2.5-3% potassium dichromate for 1 day
post chromatization
78
ideal time to perform fixation:
within 20-30 mins
79
most important reaction for maintaining tissue morphology
stabilization of proteins
80
additive fixatives examples:
formalin, mercury, osmium tetroxide
81
nonadditive fixatives examples:
alcoholic agents
82
electron microscopy section thickness
1-2 mm^2
83
light microscopy section thickness
2 cm^2
| not > 0.4 cm
84
simple fixative example:
glacial acetic acid
| solidification temp: 17 C
85
compound fixative example:
zenker's solution
2 major parts:
-mercuric chloride: shrinks tissue
-glacial acetic acid: swells tissue
86
kind of fixatives that is used for general microscopic study
microanatomical fixatives
87
kind of fixative that fixes specific parts of the cell
cytological fixatives
88
usual fixation time for formalin
24 hours
89
formalin is produced from?
a gas produced by the oxidation of methanol
90
stock solution, tends to overharden the outer surface of the tissue.
not meant to be used as fixative
40% formalin
91
working solution (unstable, may produce artefacts)
10% formalin
92
10% formalin artefacts:
white precipitates that may form after prolonged standing of solution at low temp
paraformaldehyde
93
how to remove paraformaldehyde artifact?
- filtration
| - add 10% methanol
94
10% formalin artefacts:
brown or black granules that may obscure microscopic details
acid formaldehyde hematin
95
how to remove acid formaldehyde hematin
- kardasewitsch method
- lillie's method
- saturated alcoholic picric acid*
- alcoholic KOH*
96
fixative for lipids
formol-calcium
97
fixative for electron cytochemistry
acrolein and kpg (karnovsky's)
98
disadvantage of using mercuric chloride:
- causes tissue to shrink
- decreases amount of demonstrable glycogen
- corrodes all metals, except for nickel alloy
- produces black granular deposits
99
type of fixative that is generally recommended for glycogen
alcoholic fixatives
100
disadvantage of using alcoholic fixatives
polarization (movement of glycogen granules towards the ends or poles of the cells)
101
this fixative inhibits hematoxylin
osmium tetroxide
102
storage conditions for osmium tetroxide
keep in a dark colored bottle to prevent evaporation
103
both fixative and decalcifying agent
trichloroacetic acid
104
fixative that is used at ice cold temp (-5 to 4 C)
acetone
