. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . 1% OSMIUM TET/IOXIDC IN TYRODE WITH ADDITION OF DEXTSAN (Ox) (AND SUCROSE) 0% 3% Dx Dx Dx 12 % Dx 3 % Dx + _ M sucRoa 3 % Dx ⦠OSM SUCROSE 6 % Dx ⦠0^5M SUCROSE o°c 1 24 HOURS to â > I z > (D Fig. 4. Balancing of the volume changes of pieces of tissues during osmium fixation when adding dextran and sucrose to the osmium tetroxide solution. reached in 3 hours. Thereafter a shrinkage can be observed, the speed of which is not related to the concentration. If formalin fixed specimens are followed furthe
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . 1% OSMIUM TET/IOXIDC IN TYRODE WITH ADDITION OF DEXTSAN (Ox) (AND SUCROSE) 0% 3% Dx Dx Dx 12 % Dx 3 % Dx + _ M sucRoa 3 % Dx ⦠OSM SUCROSE 6 % Dx ⦠0^5M SUCROSE o°c 1 24 HOURS to â > I z > (D Fig. 4. Balancing of the volume changes of pieces of tissues during osmium fixation when adding dextran and sucrose to the osmium tetroxide solution. reached in 3 hours. Thereafter a shrinkage can be observed, the speed of which is not related to the concentration. If formalin fixed specimens are followed further in the preparation procedures it is seen (fig. 3) that they react in a manner very similar to that described for osmium fixed material. Fixation in 4 "o formal- dehyde gives an initial swelling of 18 % after 12 hours. Dehydration and paraffin infiltration reduce the volume with 30 "o each. In methacrylate again, the shrinkage is small. The changes in specific weight are unimportant. The results obtained indicate that the swelling in the fixatives is due not only to the fixing agents themselves but in a high degree to the aqueous media in which they are dissolved. Liver pieces were suspended in Tyrode's solution of various concentra- tions at 0 C. A swelling is noted in all, even those strongly hypertonic. As expected the swelling is most pronounced in the diluted solutions and in these, maximal swelling is also reached in shorter time. Similar results are obtained with Krebs-Ringer media and also with sucrose solutions. The addition of small amounts of gelatin to physiological fluids has been recommended in order to reduce their toxical effects on cells. The addition of °(, gelatin to Tyrode's solution reduces the swelling significantly with about 20%. Fig. 4 shows that a still more pronounced effect is noted with dextran. It is possible to use dextran in much higher concentrations than is possible with gelatin without increasing the viscosity to an i
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