Effect of Colchicine and X-Radiation on the Differentiation of Human Embryonal Carcinoma*

Treatment with colchicine or x-radiation of a human embryonal carcinoma of testicular origin, which has secreted a chorionic gonadotropin-like hormone in ~0 per cent of heterografted hosts, resulted in a 2 89 times increase in the incidence of chorionic gonadotropin-secreting tumors as determined in oophorectomized and hypophysectomized animals. Lines developed from three of the tumors treated with colchicine maintained a 50 per cent incidence of gonadotropic secretion for several generations in the absence of further treatment. These lines gradually reverted to the normal ~0 per cent incidence of secretion during continued transplantation. This evidence has been interpreted as support for the contention that human embryonal carcinoma may be a stage in the development of choriocarcinoma.