A comparative study for ultrastructural localization of intracellular immunoglobulins using peroxidase conjugates.

Fixation with 4% formaldehyde/24 hours, 1% formaldehyde and 1% glutaraldehyde/1-1.5 hours and 1-1.5% glutaraldehyde/1-1.5 hours provided satisfactory ultrastructural conservation of the tissues. None of these fixatives appeared to denature IgG globulins, but formation of cross-linkages prevents conjugates from reaching antigenic sites. Weak aldehyde fixation may enhance penetration of conjugates; however, ultrastructural detail is poorly preserved and proteins will leak out from insufficiently fixed tissue, thus increasing the possibility of staining artifacts.