Papanicolaou Staining: A Technique to Visualize the Cytological Features of Tubal Cells

The fallopian tube epithelium comprises secretory cells that produce nutrient-rich fluid and ciliated cells that propel the fluid-bathed ovum toward the uterus. Morphological changes and functional loss in tubal cells are associated with fallopian tube cancer.

To visualize tubal morphology, take a tissue-smeared slide and dip it in ethanol to fix its cytological features. Rinse the slide in water to remove excess fixative.

Now, dip the slide in hematoxylin, a cationic dye that binds the negatively charged DNA, staining the nucleus blue. Rinse the slide with water followed by ethanol to prevent overstaining.

Thereafter, immerse the slide in Eosin Azure dye - a polychrome solution of Bismarck brown, Eosin Y, and Fast green mixed in phosphotungstic acid. Bismarck brown precipitates phosphotungstic acid, a mordant used by Eosin Y, and Fast green to differentially stain non-cancerous tubal cells and metabolically active cancer cells.

Repeat the water-alcohol rinsing step. Lastly, submerge the slide in xylene - a clearing agent that removes the excess stain components. Subsequently, mount the slide, and visualize it under a microscope.

The normal fallopian tube epithelium appears as an organized layer of light-blue stained, ciliated, and secretory cells. In contrast, the malignant cells in the epithelium appear as cell clusters with dark nuclei.