Histologic pattern and growth in two human testis cancers before and after transplantation to nude mice.

A yolk sac tumor of the testis and a testicular germ cell tumor with a mixed pattern were serially transplanted to athymic mice. The morphologic pattern in light microscope of each of the transplanted tumours were similar to that of the donor tumor, and both the donor and the transplanted tumors revealed alphafetoprotein reactivity by immunohistochemical staining. The observed growth of the mixed tumor in the donor and in the transplants fitted well with an estimation by the Gompertz equation. The ultrastructure of the transplanted tumors were similar to those previously described for testicular tumors with similar histologic patterns.