A pale yellow or tan discoloration of the entire tissue section, often described as a 'dirty' or 'muddy' background, typically indicates insufficient washing between steps. Throughout the IHC protocol, slides must be washed thoroughly after each incubation (primary antibody, secondary antibody, enzyme complex) to remove any unbound or loosely bound reagents. If washing is too brief or not vigorous enough, residual reagents remain in the tissue and on the slide. During the final chromogen development step, these residual enzymes (like HRP) can catalyze the formation of the colored precipitate not just at specific antigen sites, but diffusely across the tissue and even in the mounting medium. This creates a generalized, light-colored stain that obscures the specific signal. Proper washing involves immersing slides in a large volume of buffer (often PBS or TBS, sometimes with a mild detergent like Tween-20) with gentle agitation for the recommended time, and ensuring that the wash buffer is changed frequently to prevent reagent carryover.

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Zambia

• loveness Phiri – 1084 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies