Ultrastructural characteristics of nephroblastomas and their relation to DNA ploid

Abstract

Fifty-one cases of nephroblastoma were pathologically studied by light and electron microscopy as well as microspectrophotometry. Under light and electron microscope, the tumor appeared to be carcinosarcoma structurally, consisting of epithelial, sarcomatous and undifferentiated tumor cells. Their ultrastructural feature was similar to that of renal tubular epithelial cells and fibroblast. It could differentially be diagnosed from renal mesoblastic tumors by electron microscopy when the tumor was mainly composed of sarcomatous cells. Microspectrophotometer measurement showed an increased mean nuclear DNA content (DI>1.04), belonging to aneuploid tumor, which together with polyploid cells, serving as one of the important characteristics of malignant tumors. In addition, the poorer the tumor differentiation the higher was the DNA content of the tumor cells, suggesting that the measurement of nuclear DNA of tumor cells might also serve as one of signs to acertain the degree of differentiation and malignant of nephroblastomas with more preciseness than general morphological examinations.