Fixation
The process of chemically preserving biological tissue to prevent autolysis and putrefaction, typically using formalin.
Full Definition
Fixation is a critical first step in histological sample preparation in which tissue is chemically treated—most commonly with 10% neutral buffered formalin—to halt enzymatic degradation and preserve cellular morphology. Proper fixation time and temperature are essential for downstream staining and molecular analysis. Underfixation leads to poor morphology, while overfixation can mask antigens in immunohistochemistry. Editors reviewing pathology reports or laboratory protocols must ensure 'fixation' is not conflated with 'fixative,' which refers to the chemical agent itself. The term is used in both surgical pathology and cytopathology contexts.
Usage
Usage note: Do not confuse 'fixation' (the process) with 'fixative' (the reagent). Always specify the fixative agent and duration in laboratory documents.
In Context
- "The protocol specifies a fixation period of 6–48 hours in 10% neutral buffered formalin before paraffin embedding." — Laboratory standard operating procedure
- "Inadequate fixation was noted in the pathology report, which may have compromised antigen retrieval during IHC staining." — Pathology quality-assurance report