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Normal Transitional Cells

Image A

Image B

Superficial transitional cells ("umbrella cells")

  • Form the majority of cells in specimens.
  • Vary greatly in size and shape, but generally are flat, large, polygonal cells (image A).
  • Abundant thin (transparent) cytoplasm, +/- vacuolation.
  • Nuclear chromatin is dusty or finely granular (salt and pepper) without nucleoli.
  • Multinucleation (>2, <50) may be seen as a reactive change, along with small red nucleoli.

Deep transitional cells

  • Same as superficial cells, except smaller with denser blue cytoplasm (image B).
  • Includes intermediate and basal cells, which are cytologically similar.
  • Increased numbers seen with: instrumentation/catheterization; calculi; and inflammatory/neoplastic conditions.