The ultrastructure of surfaces of positively identified cells in the human urinary sediment. A correlative light and scanning electron microscopic study.

Surfaces of cells in the urinary sediment, postively identified by light microscopy (LM) were studied by scanning electron microscopy (SEM). About 35% of benign urothelial cells were characterized by the presence of short, stubby microvilli (MV). About 60% of such cells had surface microridges, and the remaining cells had surface blebs. Squamous epithelial cells were characterized primarily by microridges or by a mixture of microridges with short microvilli. Urothelial cancer cells had various surface characteristics. About 30% of these cells displayed plemorphic MV, about 10% of these cells showed short, regular MV, and the remainder appeared to be poorly preserved and had smooth surfaces, either with MV remnants or points of membrane rupture (holes or pits). The correlation between SEM surface features and the LM appearance of urothelial cancer cells was poor. Many of the most characteristic cancer cells on LM had no distinguishing SEM features. It is concluded that the application of SEM for the diagnosis of urothelial carcinoma in urine is of uncertain benefit, pending further studies.