Bone induction by Ewing's sarcoma. Transplantation into athymic nude mice.

Fresh specimens from two cases of Ewing's sarcoma were implanted in thigh muscles of nude athymic mice. Ewing's sarcomas induced differentiation of mouse-derived new bone in the same fashion as osteogenic sarcomas and chondrosarcomas. Control transplants of eight primary nonosseous and metastatic tumors did not induce bone formation. The osteoinductive action of Ewing's sarcoma is submitted as evidence of its origin from an osteogenic cell rather than from a hematopoietic cell line.