Biomedical Engineering Reference
In-Depth Information
Table 1
Common ocular fixatives
Fixative solution
Composition
Purpose/characteristics
10 % Formalin, neutral
buffered (NBF)
Formaldehyde
(37-40 %)
Distilled water
Disodium diphosphate
Monosodium
phosphate
10 %
LM, IHC
Readily available, gold standard for IHC
90 %
6.5 g
4.0 g
Davidson's fixative
Ethanol (95 %)
Formaldehyde
(37-40 %)
Glacial acetic acid
Distilled water
35 %
2%
LM
Good histological preservation of the
retina
10 %
53 %
Modified Davidson's
fixatives
Ethanol (95 %)
Formaldehyde
(37-40 %)
Glacial acetic acid
Distilled water
15 %
30 %
LM
Good histological preservation of the
retina
5%
50 %
Bouin's fixative
Picric acid (saturated
aqueous)
Formaldehyde
(37 % w/w)
Glacial acetic acid
75 %
LM
Good histological preservation of the
retina, decalcifies tissues
25 %
5%
Glutaraldehyde
and 10 % NBF
Glutaraldehyde (4 %)
10 % NBF
50 %
50 %
LM, EM
Good histological preservation
Slow penetration, requires intravitreal
injection or a window
Karnovsky's fixative
16 % paraformaldehyde
10 % glutaraldehyde
0.2 M phosphate buffer
(pH 7.4)
Distilled water
17 %
31 %
50 %
EM
Good tissue penetration and fixation
2%
LM
Excellent fixation of nuclear chromatin,
connective tissue fibers and some
cytoplasmic features
LM
light microscopy,
IHC
immunohistochemistry,
EM
electron microscopy
Zenker's
Distilled water
Potassium dichromate
Mercuric chloride
Glacial acetic acid
1l
25 g
50 g
50 g
Another commonly used fixative is 1-6 % glutaraldehyde buffer
with monobasic or dibasic sodium phosphate, which is often mixed
with another fixative [
84
,
85
]. For example, a 1:1 mixture of 4 %
glutaraldehyde and 10 % NBF is used for light microscopy and a
mixture of glutaraldehyde and paraformaldehyde has been used
for transmission electron microscopy. Advantages of using glutaral-
dehyde include (1) minimizes vacuolation of the corneal epithelium
