38
3.
FIXATION
Stock buffer
1 part
O.liVHCl
1 part
Distilled water
2 parts
2% osmium tetroxide solution
4 parts
Sucrose
0.015 gm/ml
The fixative should have a pH of about 7.4.
People associated at one time or another with the Rockefeller Institute
group have also experimented with the pH of the basic Palade formulation. These investigators generally agree that when the tissues are highly
hydrated it is desirable to buffer way over on the alkaline side at a pH of
8, or even 8.5. In general, invertebrate and embryonic tissues, as well as
protozoans, seem to be preserved better under these conditions.
People associated with the Rockefeller Institute group also have concerned themselves to some extent with specific ion effects. They have
found, for instance, that the ammonium ion must be avoided in buffers
for it destroys the membranes of the endoplasmic reticulum. On the other
hand, calcium and/or magnesium ions in little more than trace quantities
may be advantageous in preventing the extraction of "cement substances."
This is, perhaps, particularly important with delicate and highly hydrated
tissues (Palade, 1956).
Investigators at the Karolinska Institutet, led by F. S. Sjostrand, have
not felt in recent years that the hydrogen ion strength was the most important part of the fixation vehicle. Rather they have emphasized tonicity.
Investigation of this was begun by Rhodin (1954) and culminated in the
following formulation of Zetterqvist (1956). This mixture is basically the
Palade fixative with balanced salts added.
Stock buffer solution:
Sodium Veronal (barbital)
14.7 gm
Sodium acetate
9.7 gm
Distilled water to make
500
ml
Stock salt solution:
Sodium chloride
40
gm
Potassium chloride
2
gm
Calcium chloride
1
gm
Distilled water to make
500
ml
Fixative:
Buffer solution
10
ml
Salt solution
3.4 ml
3.
FIXATION
Stock buffer
1 part
O.liVHCl
1 part
Distilled water
2 parts
2% osmium tetroxide solution
4 parts
Sucrose
0.015 gm/ml
The fixative should have a pH of about 7.4.
People associated at one time or another with the Rockefeller Institute
group have also experimented with the pH of the basic Palade formulation. These investigators generally agree that when the tissues are highly
hydrated it is desirable to buffer way over on the alkaline side at a pH of
8, or even 8.5. In general, invertebrate and embryonic tissues, as well as
protozoans, seem to be preserved better under these conditions.
People associated with the Rockefeller Institute group also have concerned themselves to some extent with specific ion effects. They have
found, for instance, that the ammonium ion must be avoided in buffers
for it destroys the membranes of the endoplasmic reticulum. On the other
hand, calcium and/or magnesium ions in little more than trace quantities
may be advantageous in preventing the extraction of "cement substances."
This is, perhaps, particularly important with delicate and highly hydrated
tissues (Palade, 1956).
Investigators at the Karolinska Institutet, led by F. S. Sjostrand, have
not felt in recent years that the hydrogen ion strength was the most important part of the fixation vehicle. Rather they have emphasized tonicity.
Investigation of this was begun by Rhodin (1954) and culminated in the
following formulation of Zetterqvist (1956). This mixture is basically the
Palade fixative with balanced salts added.
Stock buffer solution:
Sodium Veronal (barbital)
14.7 gm
Sodium acetate
9.7 gm
Distilled water to make
500
ml
Stock salt solution:
Sodium chloride
40
gm
Potassium chloride
2
gm
Calcium chloride
1
gm
Distilled water to make
500
ml
Fixative:
Buffer solution
10
ml
Salt solution
3.4 ml