3.12.
PERMANGANATE FIXATIVE OF LUFT (1956)
65
Stock buffer solution:
Sodium Veronal (barbital)
Sodium acetate
Water to make
14.7 gm
9.7 gm
500 ml
Fixative:
Permanganate solution
Buffer solution
1 part
1 part
Adjust to pH 7.4-7.6
Since this fixative is used as a progressive oxidant, time becomes an
important factor. Most membrane systems are best preserved after a
short time interval of from one quarter to two hours, but in special
instances shorter or much longer periods can be desirable. The investigator will have to experiment to find the time interval most suited to his
requirements.
There is considerable doubt as to whether or not the buffer in the
vehicle contributes importantly to the properties of the fixative. In dealing with botanical material in particular, investigators frequently have
omitted this with results that apparently are nearly indistinguishable
from buffered fixatives. Mollenhauer (1959) specifically recommends unbuffered 2-5% solutions at room temperatures.
Tahmisian (1964) has worked out both buffered and unbuffered variants of permanganate fixatives that have the same freezing-point depressions as 0.9% NaCl, and are therefore isotonic with mammalian blood
cells. His formulations follow:
Buffered
fixative:
Stock buffer solution
12
ml
(the Michaelis buffer as used by Palade, Chapter 3.2)
Luft apparently originally did not think that the cation of the permanganate fixative made much difference and presumably chose the potassium
salt as the most stable soluble one. Wetzel (1961) carefully compared the
sodium salt with the potassium one using a small turbellarian worm as
KMn0 4
Distilled water to make
100
1.3 gm
0
ml
Unbuffered
fixative:
KMn0 4
NaCl
Distilled water to make
100
1.3 gm
4.5 gm
0
ml
PERMANGANATE FIXATIVE OF LUFT (1956)
65
Stock buffer solution:
Sodium Veronal (barbital)
Sodium acetate
Water to make
14.7 gm
9.7 gm
500 ml
Fixative:
Permanganate solution
Buffer solution
1 part
1 part
Adjust to pH 7.4-7.6
Since this fixative is used as a progressive oxidant, time becomes an
important factor. Most membrane systems are best preserved after a
short time interval of from one quarter to two hours, but in special
instances shorter or much longer periods can be desirable. The investigator will have to experiment to find the time interval most suited to his
requirements.
There is considerable doubt as to whether or not the buffer in the
vehicle contributes importantly to the properties of the fixative. In dealing with botanical material in particular, investigators frequently have
omitted this with results that apparently are nearly indistinguishable
from buffered fixatives. Mollenhauer (1959) specifically recommends unbuffered 2-5% solutions at room temperatures.
Tahmisian (1964) has worked out both buffered and unbuffered variants of permanganate fixatives that have the same freezing-point depressions as 0.9% NaCl, and are therefore isotonic with mammalian blood
cells. His formulations follow:
Buffered
fixative:
Stock buffer solution
12
ml
(the Michaelis buffer as used by Palade, Chapter 3.2)
Luft apparently originally did not think that the cation of the permanganate fixative made much difference and presumably chose the potassium
salt as the most stable soluble one. Wetzel (1961) carefully compared the
sodium salt with the potassium one using a small turbellarian worm as
KMn0 4
Distilled water to make
100
1.3 gm
0
ml
Unbuffered
fixative:
KMn0 4
NaCl
Distilled water to make
100
1.3 gm
4.5 gm
0
ml