The major source of the issue in the image is tissue carryover in staining.

• A. Tissue carryover in staining
• B. Cross contamination during deparaffinization
• C. Air bubbles in the mounting medium
• D. Improper fixation

Answer: (A)

Carryover staining happens when dye remnants or fragments from a previous tissue transfer onto a subsequent slide, creating ghosted areas or color that doesn’t belong to the current specimen. The image shows staining patterns that mirror a prior tissue or spillover from a previous slide, which is classic for this kind of carryover rather than an issue inherent to the current section. Preventing it relies on careful slide handling: keep slides well separated on racks, use clean staining baths and rinses, change solutions regularly, and ensure slides are completely dry before stacking or reprocessing. Other possibilities would create different problems: cross contamination during deparaffinization would more likely introduce residues from wax or multiple tissues in a way that doesn’t produce the same ghosting pattern; air bubbles manifest as round pockets in the mounting medium; improper fixation disrupts tissue morphology and staining uniformly rather than causing cross-slide transfer.