Z-5 Specialty Fixative - 1 Quart

Diluted Z-5 is designed to produce the desirable features of B-5, Bouin’s fluid and other fixatives containing mercuric salts or picric acid. However, Z-5 replaces the hazardous mercuric salts or hazardous picric acid with a zinc salt. The active ingredients in Z-5 are zinc salts and formaldehyde. Formaldehyde fixation is a two-step process. First, formaldehyde forms addition products with macromolecules. Second, the formaldehyde adduct crosslinks the macromolecules, firming the tissue. While necessary for complete fixation, the crosslinks (methylene bridges) can block access to antigenic epitopes. With diluted Z-5, both the zinc and formalin initially attach to tissue sites. Additional zinc ions then form large coordination complexes that prevent the formaldehyde from further crosslinking by simply getting in the way. The zinc constituent of diluted Z-5 gives cellular components enough rigidity without undesirable hardening. The alcohol component of diluted Z-5 increases the penetration rate of the fixative and starts the dehydration process without excessive drying. Diluted Z-5 prevents the formalin artifact described as nuclear bubbling, in which chromatin patterns are disrupted due to inadequate exposure to formalin. Enhanced H&E staining due to the mordant effect of the zinc is another diluted Z-5 benefit. With fewer methylene bridges, diluted Z-5 reduces or eliminates the need for antigen recovery procedures in immunohistochemistry.