Fine structural studies on the cytoplasmic membrane morphology of transitional cell carcinoma in men

Abstract

Transitional cell carcinomas (TCC) in the human urinary bladder were observed on the fine morphological behaviour of the plasma membrane, with special references to the morphological differences in various grades of TCC utilizing thin sections and freeze fracture replica electron microscopically. The purpose of this study is to clarify the characteristic differences between various grades of human TCC as a indicator suggestive of the TCC malignancy using electron microscopic techniques. (1) The asymmetric unit membrane seen on the luminal membrane of the superficial cells was unique in all of TCC G1 and some TCC G2 cases. In other TCC G2 and TCC G3, there observed the symmetric unit membrane. Fusiform vesicles directly beneath the luminal plasma membrane were recognized only in TCC G1. (2) Microvilli (MV) seen on the luminal plasma membrane in TCC G1 were found to have the same appearance and distribution as on the normal bladder epithelium. As the grades increased in severity, there were less MV being shorter and club-like-forms. Even deformed with bleb formation microvilli were more apparent in TCC G3 cases than in TCC G2. (3) There was no difference observed between the junctional complex of the superficial cells of the all TCC grades and normal cells. As the cellular malignancies develop, however, the interdigitation structures and desmosomal appearances situated between neighboring intermediate cells tended to decrease. (4) Intracytoplasmic tonofilaments proliferation was obvious in TCC G2, but not in G3. (5) With increasing severity of TCC grades, intramembranous particles showed significant decrease in number as seen on freeze-fracture replica. In conclusion, these results suggest that fine structural observation may prove to be a useful parameter to know the grades of TCC in human bladder tumors.