Electron immunoperoxidase stainings in sections of unfixed pure cultures of Streptococcus mutans

Unfixed as well as glutaraldehyde-fixed pelleted cells from pure cultures of Streptococcus mutans subspecies sobrinus (B13) were embedded in glycolmethacrylate. Ultrathin were sections immunoperoxidase labelled with rabbit anti-S. mutans sobrinus gamma-globulin. It was found that unfixed specimens became labelled as precisely and as distinctly as did the fixed specimens. All controls were negative.