An improved fixation technique for ultrastructural preservation of embryonic lenses

Substandard ultrastructural preservation of mitochondria in rat lenses, resulting from glutaraldehyde fixation, prompted us to apply the technique of Minassian and Huang which involved the addition of 0.1% sodium azide (NaN3), an inhibitor of mitochondrial respiration, to the fixative. As had been found in other tissue types by these investigators, we determined that the presence of NaN3 greatly improved the ultrastructure of mitochondria in embryonic lenses. That the effect of NaN3 was not strictly osmotic was established by comparison of lenses fixed in azide solution with those fixed in non-azide solutions of comparable and higher osmolalities.