Alpha-fetoprotein synthesis in tissue culture of human testicular tumors and an examination of experimental yolk sac tumors in the rat.

The slices of testicular tumors isolated from patients with high serum alpha-fetoprotein (AFP) levels were cultivated in vitro, and the synthesis of some serum proteins, including AFP, was demonstrated. The tumors were produced from yolk sac in rats by fetectomy. The tumors consisted of the various histological structures, such as of teratoma, yolk sac tumor, and very immature tumor. The tumors with yolk sac histology were able to produce AFP. The tumors induced in rats were transplantable, but the well-differentiated histology disappeared after transplantation. The capacity of AFP synthesis in transplanted tumors seemed to be maintained for generations in female rats but not in male rats.