The fact that the course of disseminated testicular carcinomas can be favorably influenced by chemotherapy has been thoroughly documented.55-61A problem now is how to blend surgery, radiation therapy, and chemotherapy into a program for the optimal management of patients with these tumors. A rational approach to this problem requires an awareness of the histogenesis and natural history of these tumors as well as a knowledge of the biological peculiarities of the different histological types. The tumors which are of concern here arise in the "germ cell" in the testicular tubule. Neoplastic change in this totipotential cell can produce a spectrum of tumors, depending on the state of differentiation in the normal cell which undergoes neoplasia and on the degree to which differentiation continues in the cancer cell.62Teratocarcinoma and choriocarcinoma can evolve from embryonal carcinoma. Electron microscopic studies have revealed an evolution of the submicroscopic cellular organization