Buffered phenol formaldehyde (pH 7.0 and pH 5.5): improved fixation in an enclosed tissue processor

The addition of 2% phenol has a marked adjuvant effect on 4% formaldehyde as a fixative. Sequential use of phenol formaldehyde buffered to pH 7.0 and pH 5.5 results in improved fixation in material rapidly advanced to paraffin in an enclosed tissue processor. Sections stained with alum haematoxylin and eosin show improved nuclear and cytoplasmic detail, reduced tissue shrinkage and an absence of formalin pigment. Excellent results are obtained with conventional special stains and immunoperoxidase methods.