A Genetically Caused Embryonal Ectodermal Tumor in the Mouse23

Abstract

This study was conducted to determine whether a gene influencing the process of differentiation could produce an abnormally differentiated tissue that was at the same time malignant. Thus the malignant potential of the overgrown primitive streak mass of t^w18/t^w18 embryos was investigated by their transplantation into adult testes. Fifteen of forty-six 8-day t^w18/t^w18 embryos, when grafted for over 28 days, produced histologically malignant growths, whereas grafts of their normal littermates became benign teratomas. The malignant tumors resembled neuroblastomas or medulloblastomas with a limited number of ectodermally derived teratomatous elements. A series of 7-day embryos was also transplanted and 5 malignant tumors resulted that were characterized by the same proliferating neuroepithelium. A few malignancies were transplanted secondarily, but all were lost due to their immunological rejection or differentiation into adult-type mature ectodermal derivatives. A discussion of the origin of this type of tumor is presented.