1. Tissue Preparation: The tissue sample is fixed and sectioned to preserve morphology and antigenicity. 2. Blocking and Primary Antibody Application: Non-specific binding sites are blocked, and a primary antibody specific to the target antigen is applied. 3. Secondary Antibody Application: A secondary antibody conjugated with an enzyme (e.g., horseradish peroxidase) is applied. 4. Chromogen Application: The chromogenic substrate is added. The enzyme catalyzes the reaction, producing a colored precipitate at the site of the antigen.
