A STUDY OF OSMIUM TETROXIDE FIXATION

Abstract

The specific conditions of osmium fixation have been studied on gelatin gels and bovine pancreas. Protein (gelatin)-bound osmium can be quantitated by a modification of the Majumdar and Sen Gupta test, free and tissue (pancreas)-bound osmium by a modified Bahr test. Using these two methods, the depth of OsO₄ penetration after increasing the times of fixation, the osmium concentration gradients and the total concentration of free and bound osmium at given spots within gelatin and tissue blocks have been determined. Warburg type experiments on suspended yeast cells and leukocytes demonstrate that 1% OsO₄ stops cell respiration completely only after 40-min incubation. Formalin, 1%, is a more effective respiratory inhibitor.