A quantitative study of nuclear DNA of trophoblastic cells: proliferation kinetics.

The nuclear DNA contents of labeled and unlabeled nuclei of trophoblastic cells of 8 normal pregnancies, 2 missed abortions, and 14 cases of trophoblastic diseases were measured by Feulgen-DNA cytofluorometry combined with autoradiography. Syncytiotroblasts were rarely labeled and were considered to be inactive with regard to cell proliferation. Most of the labeled cells were cytotrophoblasts. The predominantly labeled cells ranged between 2 and 4C in cases of normal pregnancy and missed abortion, and a shift to a higher ploidy was seen in the more grave trophoblastic disease. From the point of cellular proliferation kinetics of trophoblastic cells, it is presumed that the cells in cases of normal pregnancy and type I hydatidiform mole are in the 2C cell cycle and in type II hydatidiform mole and in invasive mole there are heterogeneous cell populations, most of which are in the 2C cell cycle while the remaining are undergoing polyploidization or aneuploidization. In choriocarcinoma, the cells are not in the 2C cell cycle and also are probably undergoing polyploidization or aneuploidization in the hyper-4C area.