[Human yolk sac tumor of the thymus heterotransplanted into nude mice].

A human yolk sac tumor of the thymus (YSK-1) was transplanted into athymic nude mice. Histological and ultrastructural investigations revealed that the YSK-1 tumor, even after serial transplantation in nude mice, characteristically displayed Schiller-Duval bodies, endodermal sinus structures and ultrastructural profiles, numerous microvilli, desmosome-like cell attachments, annulate lamellar structures, many lipid droplets and interspersed glycogen particles. Serological study by radioimmunoassay demonstrated AFP, CEA, HCG, alpha 1-AT and transferrin in the sera and cyst fluid of the tumor-bearing nude mice. Immunohistochemical investigation using the PAP method showed that the YSK-1 cells produced CEA, HCG, alpha 1-AT, transferrin as well as AFP. The increase in the level of AFP paralleled the increase in tumor size.